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HistorySep 01, 2021 - 12:00 a.m.

Security update for dovecot23 (moderate)


0.036 Low




An update that solves two vulnerabilities, contains one
feature and has one errata is now available.


This update for dovecot23 fixes the following issues:

Update dovecot to version 2.3.15 (jsc#SLE-19970):

Security issues fixed:

  • CVE-2021-29157: Dovecot does not correctly escape kid and azp fields in
    JWT tokens. This may be used to supply attacker controlled keys to
    validate tokens, if attacker has local access. (bsc#1187418) Local
    attacker can login as any user and access their emails
  • CVE-2021-33515: On-path attacker could have injected plaintext commands
    before STARTTLS negotiation that would be executed after STARTTLS
    finished with the client. (bsc#1187419) Attacker can potentially steal
    user credentials and mails
  • Add TSLv1.3 support to min_protocols.
  • Allow configuring ssl_cipher_suites. (for TLSv1.3+)
  • acl: Add acl_ignore_namespace setting which allows to entirely ignore
    ACLs for the listed namespaces.
  • imap: Support official RFC8970 preview/snippet syntax. Old methods of
    retrieving preview information via IMAP commands (“SNIPPET and PREVIEW
    with explicit algorithm selection”) have been deprecated.
  • imapc: Support INDEXPVT for imapc storage to enable private message
    flags for cluster wide shared mailboxes.
  • lib-storage: Add new events: mail_opened, mail_expunge_requested,
    mail_expunged, mail_cache_lookup_finished. See
  • zlib, imap-compression, fs-compress: Support compression levels that the
    algorithm supports. Before, we would allow hardcoded value between 1 to
    9 and would default to 6. Now we allow using per-algorithm value range
    and default to whatever default the algorithm specifies.
  • *-login: Commands pipelined together with and just after the
    authenticate command cause these commands to be executed twice. This
    applies to all protocols that involve user login, which currently
    comprises of imap, pop3, submisision and managesieve.
  • *-login: Processes are supposed to disconnect the oldest non-logged in
    connection when process_limit was reached. This didn’t actually happen
    with the default “high-security mode” (with service_count=1) where each
    connection is handled by a separate process.
  • *-login: When login process reaches client/process limits, oldest client
    connections are disconnected. If one of these was still doing anvil
    lookup, this caused a crash. This could happen only if the login process
    limits were very low or if the server was overloaded.
  • Fixed building with link time optimizations (-flto).
  • auth: Userdb iteration with passwd driver does not always return all
    users with some nss drivers.
  • dsync: Shared INBOX not synced when “mail_shared_explicit_inbox” was
    disabled. If a user has a shared mailbox which is another user’s INBOX,
    dsync didn’t include the mailbox in syncing unless explicit naming is
    enabled with “mail_shared_explicit_inbox” set to “yes”.
  • dsync: Shared namespaces were not synced with “-n” flag.
  • dsync: Syncing shared INBOX failed if mail_attribute_dict was not set.
    If a user has a shared mailbox that is another user’s INBOX, dsync
    failed to export the mailbox if mail attributes are disabled.
  • fts-solr, fts-tika: Using both Solr FTS and Tika may have caused HTTP
    requests to assert-crash: Panic: file http-client-request.c: line 1232
    (http_client_request_send_more): assertion failed: (req->payload_input
    != NULL)
  • fts-tika: 5xx errors returned by Tika server as indexing failures.
    However, Tika can return 5xx for some attachments every time. So the 5xx
    error should be retried once, but treated as success if it happens on
    the retry as well. v2.3 regression.
  • fts-tika: v2.3.11 regression: Indexing messages with fts-tika may have
    resulted in Panic: file message-parser.c: line 802
    (message_parser_deinit_from_parts): assertion failed:
    (ctx->nested_parts_count == 0 || i_stream_have_bytes_left(ctx->input))
  • imap: SETMETADATA could not be used to unset metadata values. Instead
    NIL was handled as a “NIL” string. v2.3.14 regression.
  • imap: IMAP BINARY FETCH crashes at least on empty base64 body: Panic:
    file index-mail-binary.c: line 358 (blocks_count_lines): assertion
    failed: (block_count == 0 || block_idx+1 == block_count)
  • imap: If IMAP client using the NOTIFY command was disconnected while
    sending FETCH notifications to the client, imap could crash with Panic:
    Trying to close mailbox INBOX with open transactions.
  • imap: Using IMAP COMPRESS extension can cause IMAP connection to hang
    when IMAP commands are >8 kB long.
  • imapc: If remote server sent BYE but didn’t immediately disconnect, it
    could cause infinite busy-loop.
  • lib-index: Corrupted cache record size in dovecot.index.cache file could
    have caused a crash (segfault) when accessing it.
  • lib-oauth2: JWT token time validation now works correctly with 32-bit
  • lib-ssl-iostream: Checking hostnames against an SSL certificate was
  • lib-storage: Corrupted in dovecot.index.cache may have
    resulted in Panic: file imap-bodystructure.c: line 206
    (part_write_body): assertion failed: (text == ((part->flags &
  • lib-storage: Index rebuilding (e.g. via doveadm force-resync) didn’t
    preserve the “hdr-pop3-uidl” header. Because of this, the next pop3
    session could have accessed all of the emails’ metadata to read their
    POP3 UIDL (opening dbox files).
  • listescape: When using the listescape plugin and a shared namespace the
    plugin didn’t work properly anymore resulting in errors like: “Invalid
    mailbox name: Name must not have ‘/’ character.”
  • lmtp: Connection crashes if connection gets disconnected due to multiple
    bad commands and the last bad command is BDAT.
  • lmtp: The Dovecot-specific LMTP parameter XRCPTFORWARD was blindly
    forwarded by LMTP proxy without checking that the backend has support.
    This caused a command parameter error from the backend if it was running
    an older Dovecot release. This could only occur in more complex setups
    where the message was proxied twice; when the proxy generated the
    XRCPTFORWARD parameter itself the problem did not occur, so this
    only happened when it was forwarded.
  • lmtp: The LMTP proxy crashes with a panic when the remote server replies
    with an error while the mail is still being forwarded through a
    DATA/BDAT command.
  • lmtp: Username may have been missing from lmtp log line prefixes when it
    was performing autoexpunging.
  • master: Dovecot would incorrectly fail with haproxy 2.0.14 service
  • master: Systemd service: Dovecot announces readiness for accepting
    connections earlier than it should. The following environment variables
    are now imported automatically and can be omitted from
    import_environment setting: NOTIFY_SOCKET LISTEN_FDS LISTEN_PID.
  • master: service { process_min_avail } was launching processes too slowly
    when master was forking a lot of processes.
  • util: Make the example script POSIX shell compatible.
  • Added new aliases for some variables. Usage of the old ones is possible,
    but discouraged. (These were partially added already to v2.3.13.) See
    for more information.
  • Optimize imap/pop3/submission/managesieve proxies to use less CPU at the
    cost of extra memory usage.
  • Remove autocreate, expire, snarf and mail-filter plugins.
  • Remove cydir storage driver.
  • Remove XZ/LZMA write support. Read support will be removed in future
  • doveadm -D: Add timestamps to debug output even when
    LOG_STDERR_TIMESTAMP environment variable is not set. Timestamp format
    is taken from log_timestamp setting.
  • If BROKENCHAR or listescape plugin is used, the escaped folder names may
    be slightly different from before in some situations. This is unlikely
    to cause issues, although caching clients may redownload the folders.
  • imapc: It now enables BROKENCHAR=~ by default to escape remote folder
    names if necessary. This also means that if there are any ‘~’ characters
    in the remote folder names, they will be visible as “~7e”.
  • imapc: When using local index files folder names were escaped on
    filesystem a bit differently. This affects only if there are folder
    names that actually require escaping, which isn’t so common. The old
    style folders will be automatically deleted from filesystem.
  • stats: Update exported metrics to be compliant with OpenMetrics standard.
  • doveadm: Add an optional ‘-p’ parameter to metadata list command. If
    enabled, “/private”, and “/shared” metadata prefixes will be prepended
    to the keys in the list output.
  • doveconf: Support environment variables in config files. See
    /#environment-variables for more details.
  • indexer-worker: Change indexer to disconnect from indexer-worker after
    each request. This allows service indexer-worker’s service_count &
    idle_kill settings to work. These can be used to restart indexer-worker
    processes once in a while to reduce their memory usage.
  • auth: “nodelay” with various authentication mechanisms such as apop and
    digest-md5 crashed AUTH process if authentication failed.
  • auth: Auth lua script generating an error triggered an assertion
    failure: Panic: file db-lua.c: line 630 (auth_lua_call_password_verify):
    assertion failed: (lua_gettop(script->L) == 0).
  • configure: Fix libunwind detection to work on other than x86_64 systems.
  • doveadm-server: Process could crash if logging was done outside command
    handling. For example http-client could have done debug logging
    afterwards, resulting in either segfault or Panic: file http-client.c:
    line 642 (http_client_context_close): assertion failed:
    (cctx->clients_list == NULL).
  • dsync: Folder name escaping with BROKENCHAR didn’t work completely
    correctly. This especially caused problems with dsync-migrations using
    imapc where some of the remote folder names may not have been accessible.
  • dsync: doveadm sync + imapc doesn’t always sync all mails when doing an
    incremental sync (-1), which could lead to mail loss when it’s used for
    migration. This happens only when GUIDs aren’t used (i.e. imapc without
  • fts-tika: When tika server returns error, some mails cause Panic: file
    message-parser.c: line 802 (message_parser_deinit_from_parts): assertion
    failed: (ctx->nested_parts_count == 0 ||
  • lib-imap: imapc parsing illegal BODYSTRUCTUREs with NILs could have
    resulted in crashes. This exposed that Dovecot was wrongly accepting
    atoms in “nstring” handling. Changed the IMAP parsing to be more strict
    about this now.
  • lib-index: If dovecot.index.cache has corrupted message size, fetching
    BODY/BODYSTRUCTURE may cause assert-crash: Panic: file index-mail.c:
    line 1140 (index_mail_parse_body_finish): assertion failed:
    (mail-> != NULL).
  • lib-index: Minor error handling and race condition fixes related to
    rotating dovecot.index.log. These didn’t usually cause problems, unless
    the log files were rotated rapidly.
  • lib-lua: Lua scripts using coroutines or lua libraries using coroutines
    (e.g., cqueues) panicked.
  • Message PREVIEW handled whitespace wrong so first space would get eaten
    from between words.
  • FTS and message PREVIEW (snippet) parsed HTML &entities case-sensitively.
  • lib-mail: When max nested MIME parts were reached, IMAP BODYSTRUCTURE
    was written in a way that may have caused confusion for IMAP clients and
    also Dovecot itself when parsing it. The truncated part is now written
    out using application/octet-stream MIME type.
  • lib-oauth2: HS512 and HS384 JWT token algorithms crash when you try to
    use them: Panic: file hmac.c: line 26 (hmac_init): assertion failed:
    (meth->context_size <= MAC_MAX_CONTEXT_SIZE).
  • event filters: NOT keyword did not have the correct associativity.
  • Ignore ECONNRESET when closing socket. This avoids logging useless
    errors on systems like FreeBSD.
  • event filters: event filter syntax error may lead to Panic: file
    event-filter.c: line 137 (event_filter_parse): assertion failed:
    (state.output == NULL)
  • lib: timeval_cmp_margin() was broken on 32-bit systems. This could
    potentially have caused HTTP timeouts to be handled incorrectly.
  • log: instance_name wasn’t used as syslog ident by the log process.
  • master: After a service reached process_limit and client_limit, it could
    have taken up to 1 second to realize that more client connections became
    available. During this time client connections could have been
    unnecessarily rejected and a warning logged: Warning: service(…):
    process_limit (…) reached, client connections are being dropped
  • stats: Crash would occur when generating openmetrics data for metrics
    using aggregating functions.
  • stats: Event filters comparing against empty strings crash the stats
  • CVE-2020-24386: Specially crafted command can cause IMAP hibernate to
    allow logged in user to access other people’s emails and filesystem
  • Metric filter and global event filter variable syntax changed to a
    SQL-like format. See
  • auth: Added new aliases for %{variables}. Usage of the old ones is
    possible, but discouraged.
  • auth: Removed RPA auth mechanism, SKEY auth mechanism, NTLM auth
    mechanism and related password schemes.
  • auth: Removed passdb-sia, passdb-vpopmail and userdb-vpopmail.
  • auth: Removed postfix postmap socket
  • auth: Added new fields for auth server events. These fields are now also
    available for all auth events. See
    for details.
  • imap-hibernate: Added imap_client_hibernated, imap_client_unhibernated
    and imap_client_unhibernate_retried events. See for details.
  • lib-index: Added new mail_index_recreated event. See
  • lib-sql: Support TLS options for cassandra driver. This requires
    cpp-driver v2.15 (or later) to work reliably.
  • lib-storage: Missing $HasAttachment / $HasNoAttachment flags are now
    added to existing mails if mail_attachment_detection_option=add-flags
    and it can be done inexpensively.
  • login proxy: Added login_proxy_max_reconnects setting (default 3) to
    control how many reconnections are attempted.
  • login proxy: imap/pop3/submission/managesieve proxying now supports
    reconnection retrying on more than just connect() failure. Any error
    except a non-temporary authentication failure will result in reconnect
  • auth: Lua passdb/userdb leaks stack elements per call, eventually
    causing the stack to become too deep and crashing the auth or
    auth-worker process.
  • auth: SASL authentication PLAIN mechanism could be used to trigger read
    buffer overflow. However, this doesn’t seem to be exploitable in any way.
  • auth: v2.3.11 regression: GSSAPI authentication fails because dovecot
    disallows NUL bytes for it.
  • dict: Process used too much CPU when iterating keys, because each key
    used a separate write() syscall.
  • doveadm-server: Crash could occur if logging was done outside command
    handling. For example http-client could have done debug logging
    afterwards, resulting in either segfault or Panic: file http-client.c:
    line 642 (http_client_context_close): assertion failed:
    (cctx->clients_list == NULL).
  • doveadm-server: v2.3.11 regression: Trying to connect to doveadm server
    process via starttls assert-crashed if there were no ssl=yes listeners:
    Panic: file master-service-ssl.c: line 22 (master_service_ssl_init):
    assertion failed: (service->ssl_ctx_initialized).
  • fts-solr: HTTP requests may have assert-crashed: Panic: file
    http-client-request.c: line 1232 (http_client_request_send_more):
    assertion failed: (req->payload_input != NULL)
  • imap: IMAP NOTIFY could crash with a segmentation fault due to a bad
    configuration that causes errors. Sending the error responses to the
    client can cause the segmentation fault. This can for example happen
    when several namespaces use the same mail storage location.
  • imap: IMAP NOTIFY used on a shared namespace that doesn’t actually exist
    (e.g. public namespace for a nonexistent user) can crash with a panic:
    Panic: Leaked view for index /tmp/home/asdf/mdbox/dovecot.list.index:
    Opened in (null):0
  • imap: IMAP session can crash with QRESYNC extension if many changes are
    done before asking for expunged mails since last sync.
  • imap: Process might hang indefinitely if client disconnects after
    sending some long-running commands pipelined, for example FETCH+LOGOUT.
  • lib-compress: Mitigate crashes when configuring a not compiled in
    compression. Errors with compression configuration now distinguish
    between not supported and unknown.
  • lib-compression: Using xz/lzma compression in v2.3.11 could have written
    truncated output in some situations. This would result in “Broken pipe”
    read errors when trying to read it back.
  • lib-compression: zstd compression could have crashed in some situations:
    Panic: file ostream.c: line 287 (o_stream_sendv_int): assertion failed:
  • lib-dict: dict client could have crashed in some rare situations when
    iterating keys.
  • lib-http: Fix several assert-crashes in HTTP client.
  • lib-index: v2.3.11 regression: When mails were expunged at the same time
    as lots of new content was being saved to the cache (e.g. cache file was
    lost and is being re-filled) a deadlock could occur with
    dovecot.index.cache / dovecot.index.log.
  • lib-index: v2.3.11 regression: dovecot.index.cache file was being purged
    (rewritten) too often when it had a field that hadn’t been accessed for
    over 1 month, but less than 2 months. Every cache file change caused a
    purging in this situation.
  • lib-mail: MIME parts were not returned correctly by Dovecot MIME parser.
    Regression caused by fixing CVE-2020-12100.
  • lib-mail: When max nested MIME parts were reached, IMAP BODYSTRUCTURE
    was written in a way that may have caused confusion for both IMAP
    clients and Dovecot itself when parsing it. The truncated part is now
    written out using application/octet-stream MIME type.
  • lib-mail: v2.3.11 regression: Mail delivery / parsing crashed when the
    10000th MIME part was message/rfc822 (or if parent was
    multipart/digest): Panic: file message-parser.c: line 167
    (message_part_append): assertion failed: (ctx->total_parts_count <=
  • lib-oauth2: Dovecot incorrectly required oauth2 server introspection
    reply to contain username with invalid token.
  • lib-ssl-iostream, lib-dcrypt: Fix building with OpenSSL that has
    deprecated APIs disabled.
  • lib-storage: When mail’s size is different from the cached one (in
    dovecot.index.cache or Maildir S=size in the filename), this is handled
    by logging “Cached message size smaller/larger than expected” error.
    However, in some situations this also ended up crashing with: Panic:
    file istream.c: line 315 (i_stream_read_memarea): assertion failed:
    (old_size <= _stream->pos - _stream->skip).
  • lib-storage: v2.3 regression: Copying/moving mails was taking much more
    memory than before. This was mainly visible when copying/moving
    thousands of mails in a single transaction.
  • lib-storage: v2.3.11 regression: Searching messages assert-crashed
    (without FTS): Panic: file message-parser.c: line 174
    (message_part_finish): assertion failed: (ctx->nested_parts_count > 0).
  • lib: Dovecot v2.3 moved signal handlers around in ioloops, causing more
    CPU usage than in v2.2.
  • lib: Fixed JSON parsing: '' escape sequence may have wrongly resulted
    in error if it happened to be at read boundary. Any NUL characters and
    ‘\u0000’ will now result in parsing error instead of silently truncating
    the data.
  • lmtp, submission: Server may hang if SSL client connection disconnects
    during the delivery. If this happened repeated, it could have ended up
    reaching process_limit and preventing any further lmtp/submission
  • lmtp: Proxy does not always properly log TLS connection problems as
    errors; in some cases, only a debug message is logged if enabled.
  • lmtp: The LMTP service can hang when commands are pipelined. This can
    particularly occur when one command in the middle of the pipeline fails.
    One example of this occurs for proxied LMTP transactions in which the
    final DATA or BDAT command is pipelined after a failing RCPT command.
  • login-proxy: The login_source_ips setting has no effect, and therefore
    the proxy source IPs are not cycled through as they should be.
  • master: Process was using 100% CPU in some situations when a broken
    service was being throttled.
  • pop3-login: POP3 login would fail with “Input buffer full” if the
    initial response for SASL was too long.
  • stats: Crash would occur when generating openmetrics data for metrics
    using aggregating functions.

Update pigeonhole to version 0.5.15

  • CVE-2020-28200: Sieve interpreter is not protected against abusive
    scripts that claim excessive resource usage. Fixed by limiting the user
    CPU time per single script execution and cumulatively over several
    script runs within a configurable timeout period. Sufficiently large CPU
    time usage is summed in the Sieve script binary and execution is blocked
    when the sum exceeds the limit within that time. The block is lifted
    when the script is updated after the resource usage times out.
    (bsc#1187420) Attacker can DoS the mail delivery system (jsc#PM-2746)
    ECO: Dovecot 2.3.15 version upgrade
  • Disconnection log messages are now more standardized across services.
    They also always now start with “Disconnected” prefix.
  • managesieve: Commands pipelined together with and just after the
    authenticate command cause these commands to be executed twice.
  • duplicate: The test was handled badly in a multiscript (sieve_before,
    sieve_after) scenario in which an earlier script in the sequence with a
    duplicate test succeeded, while a later script caused a runtime failure.
    In that case, the message is recorded for duplicate tracking, while the
    message may not actually have been delivered in the end.
  • editheader: Sieve interpreter entered infinite loop at startup when the
    “editheader” configuration listed an invalid header name. This problem
    can only be triggered by the administrator.
  • relational: The Sieve relational extension can cause a segfault at
    compile time. This is triggered by invalid script syntax. The segfault
    happens when this match type is the last argument of the test command.
    This situation is not possible in a valid script; positional arguments
    are normally present after that, which would prevent the segfault.
  • sieve: For some Sieve commands the provided mailbox name is not properly
    checked for UTF-8 validity, which can cause assert crashes at runtime
    when an invalid mailbox name is encountered. This can be caused by the
    user by writing a bad Sieve script involving the affected commands
    (“mailboxexists”, “specialuse_exists”). This can be triggered by the
    remote sender only when the user has written a Sieve script that passes
    message content to one of the affected commands.
  • sieve: Large sequences of 8-bit octets passed to certain Sieve commands
    that create or modify message headers that allow UTF-8 text (vacation,
    notify and addheader) can cause the delivery or IMAP process (when
    IMAPSieve is used) to enter a memory-consuming semi-infinite loop that
    ends when the process exceeds its memory limits. Logged in users can
    cause these hangs only for their own processes.

Patch Instructions:

To install this openSUSE Security Update use the SUSE recommended installation methods
like YaST online_update or “zypper patch”.

Alternatively you can run the command listed for your product:

  • openSUSE Leap 15.3:

    zypper in -t patch openSUSE-SLE-15.3-2021-2892=1

openSUSE Leap15.3aarch64< - openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):- openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):.aarch64.rpm
openSUSE Leap15.3ppc64le< - openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):- openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):.ppc64le.rpm
openSUSE Leap15.3s390x< - openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):- openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):.s390x.rpm
openSUSE Leap15.3x86_64< - openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):- openSUSE Leap 15.3 (aarch64 ppc64le s390x x86_64):.x86_64.rpm