curl: [HIGH] CWE-22 — Path Traversal in FTP Wildcard Download via Unencoded `.` in Escaped Filenames

Summary A malicious or MITM'd FTP server can cause a client using CURLOPTWILDCARDMATCH to download files outside the intended remote directory, by returning a LIST response with a filename containing .. path-traversal sequences. Details In the CURLWCDOWNLOADING state lib/ftp.c:4079-4095, each...

curl: Missing applicability validation allows non-applicable HTTPS RR to reach ECH processing

Summary The HTTPS RR applicability check Curlhttpsrrapplicable is applied before ALPN selection, but the same check is not applied consistently in the ECH initialization paths. When an HTTPS RR is not applicable to the active connection, curl correctly reports it as not applicable and avoids usin...

curl: Windows filename sanitizer misses Unicode COM/LPT reserved device names

Hi all, I found a way for a server-selected Windows filename to bypass curl's reserved DOS device-name sanitizer. With curl -O -J, a Content-Disposition filename such as COM¹, COM², COM³, LPT¹, LPT², or LPT³ is left unchanged, even though Windows treats all six as reserved device names. Curl...

curl: Use-after-free of the internal multi->admin easy handle via the documented CURLMOPT_NOTIFYFUNCTION callback

Summary: curlmultiinit creates an internal easy handle multi-admin and marks it state.internal = TRUE lib/multi.c:248. The CURLMOPTNOTIFYFUNCTION callback is handed that internal handle on CURLMNOTIFYINFOREAD lib/multintfy.c:109, and the option documentation invites callbacks to remove and clean ...

curl: Encoded slash traversal in the IPFS/IPNS URL rewrite escapes the configured gateway namespace

curl 8.22.0's IPFS/IPNS CLI rewrite decodes the user path after its first dot-segment cleanup, then places that decoded path after the configured gateway base and /ipfs/ or /ipns/ namespace. An encoded slash can therefore become a structural separator too late for the first cleanup, and the final...

curl: HTTP/1.1 response framing violation and unsafe connection reuse when transfer decoding is disabled

Summary: libcurl can incorrectly reuse an HTTP/1.1 connection after a response containing both Content-Length and a non-chunked Transfer-Encoding when transfer decoding is disabled with CURLOPTHTTPTRANSFERDECODING = 0L --raw behavior. In this state, libcurl can treat Content-Length as the respons...

curl: Out-of-bounds read in curl_formadd when CURLFORM_NAMELENGTH is explicitly 0

Hi all, I've discovered a heap out-of-bounds read in curlformadd that causes libcurl to silently read past a caller-supplied buffer and transmit the leaked contents to the remote server. It's confirmed under ASan and reachable without violating any documented precondition. Impact An application...

curl: libcurl LDAP LDIF: entry DN and attribute names written without RFC 2849 base64 encoding, allowing server line injection

Summary: curl 8.22.0 base64-encodes LDAP attribute values that aren't RFC 2849 SAFE-STRINGs commit 2ba2fe3540, issue 22339, but the entry DN and the attribute names are still written to the LDIF output verbatim. In lib/openldap.c oldaprecv that's the DN clientwritedata, STRCONST"DN: ", bv.bvval,...

curl: TELNET control and environment data bypass HTTPS-proxy TLS

Hi, I found a way to make libcurl send TELNET credential and environment data in cleartext to a TELNET origin, even when the connection is supposedly protected by an HTTPS proxy tunnel. The tunnel's TLS never sees it. The bug For telnet:// routed through an HTTPS proxy, generic connection setup...

curl: Socket API drops expired timeouts for transfers queued behind a connection limit

Hi all, I found a way to make libcurl silently and permanently drop a transfer's CURLOPTTIMEOUTMS/CURLOPTCONNECTTIMEOUTMS deadline. It happens when that transfer is queued behind a connection-count limit and the application drives libcurl through the event-driven curlmultisocketaction API instead...

Essity: Unauthenticated API allows reading, writing to and deleting any user's private chat history on ████████

An unauthenticated API was discovered that allowed reading, writing to, and deleting any user's private chat history on the organization's internal chatbot application. The API had no authentication mechanism in place, allowing an attacker to list all conversations, retrieve the complete message...

curl: TLS session resumption client cert bypass with CURLOPT_SSL_CTX_FUNCTION

AI use Cipher, by Causal Security, was used to find, exploit and confirm this issue. A further check was carried out to establish, as far as is possible from outside the project, that it is neither a duplicate of an existing report or advisory nor documented as intended behaviour. Everything belo...

HackerOne: HackerOne Code sends live password-reset tokens to Segment in automatic page events

A vulnerability was discovered in the HackerOne Code application, where opening a password-reset link automatically sent the complete unused 64-character reset token to Segment as the page loaded, before the reset form was submitted. The token was present in various fields of the Segment page...

Ruby on Rails: Action Text to_markdown: <code>/<pre> content escapes its delimiter, letting a stored body inject arbitrary Markdown

Summary ActionText::Contenttomarkdown escapes text nodes so that a stored rich text body cannot turn into Markdown syntax. Text whose immediate parent is or is exempt from that escaping MarkdownConversion::SKIPESCAPINGPARENTS and is instead kept inert by the delimiter its visitor wraps around it...

curl: HTTP Digest nonce reused across an https→http scheme change on the same handle

Hi all, Last one from my side. Looks like https://hackerone.com/reports/3793260 was not patched completely correctly, and libcurl emit a live Authorization: Digest response computed from a nonce/realm it only ever received over TLS preemptively over plaintext HTTP, on a reused easy handle that...

curl: Apple SecTrust fallback ignores CURLOPT_CRLFILE, letting a revoked cert pass

When libcurl is built with USEAPPLESECTRUST and the native Apple trust store is in use, a certificate that OpenSSL/GnuTLS rejects because it is on the operator's CURLOPTCRLFILE list is re-checked by Apple's SecTrust API instead, and SecTrust is never told about that CRL file at all. The bug...

curl: IMAP connection reuse runs requests in the wrong case-sensitive mailbox

When libcurl reuses an authenticated IMAP connection, lib/imap.c:2071-2089 uses curlstrequal to decide whether the requested mailbox is already selected. RFC 9051 section 5.1 requires clients to work with servers where non-INBOX mailbox names are case-sensitive, while only INBOX is guaranteed to ...

curl: 56: IBM i CL wrapper `parse_command_line()` never enters quote mode

Summary In projects/OS400/curlcl.c, the parsecommandline function initializes quote to '\0' but no code path ever assigns an opening ' or " to it. The close-quote check line 82, quote-aware backslash handling line 88, and unterminated-quote error line 106 are all dead code. As a result, quote...

curl: 55: Heap-buffer-overflow read in `curl_formadd_ccsid()` with binary form data

Summary curlformaddccsid in projects/OS400/ccsidcurl.c performs a heap-buffer-overflow read when CURLFORMCONTENTTYPE appears before an explicit length CURLFORMCONTENTLEN / CURLFORMCONTENTSLENGTH for binary CURLFORMCOPYCONTENTS data containing embedded NUL bytes. The overread bytes are copied into...

curl: 53: HTTP/1 CONNECT chunked-407 trailers bypass CURLOPT_SUPPRESS_CONNECT_HEADERS and lose CURLH_CONNECT classification

Summary When an HTTP/1 proxy returns a chunked 407 Proxy Authentication Required during a CONNECT handshake, any trailer fields in that response are delivered to the header callback even when CURLOPTSUPPRESSCONNECTHEADERS is enabled, and are classified as CURLHTRAILER instead of CURLHCONNECT in t...

curl: 50: CMake `HTTP_ONLY` does not disable SSH backends — SCP and SFTP remain usable

Summary The CMake HTTPONLY=ON option is documented as "Disable all protocols except HTTP" CMakeLists.txt:538, but the implementation CMakeLists.txt:541-557 only sets CURLDISABLE flags for non-SSH protocols. It does not disable CURLUSELIBSSH2 or CURLUSELIBSSH. Since CURLUSELIBSSH2 defaults to ON, ...

curl: 57: Heap out-of-bounds read in `curl_easy_escape_ccsid()` / `curl_easy_unescape_ccsid()`

Summary curleasyescapeccsid and curleasyunescapeccsid in projects/OS400/ccsidcurl.c discard the converted byte count returned by dynconvert and pass 0 to the downstream curleasyescape / curleasyunescape. When the caller supplies a positive explicit length with non-NUL-terminated input, dynconvert...

curl: 54: Rejected HTTP/2 push destroys MIME callback state still used by parent (use-after-free)

Summary pushpromise in lib/http2.c duplicates the parent easy handle before validating the pushed URL. When validation fails e.g. unsupported scheme, discardnewhandle destroys the duplicate. For callback-backed MIME uploads, Curlmimeduppart copies the same readfunc, freefunc, and arg pointer, so...

curl: 49: Cookie-jar save transfers group access to a different GID

Summary Curlfopen copies the old cookie jar's permission bits onto a newly created temp file, but the temp file may receive a different GID the process's primary group instead of the old file's group. After rename, group-permission bits that were intended for one group now authorize a different...

curl: 42: `VMS_STS` macro typo (`< 3` vs `<< 3`) turns curl failures into successful OpenVMS conditions

Summary VMSSTS in src/toolvms.h line 46 uses a comparison 3 where a left-shift 3 is intended. This causes VMSSTSHIDE to evaluate to 0x10000001 instead of 0x10000000, setting bit 0 the OpenVMS success bit. When curl runs under DCL with --silent and without --show-error, the mask is ORed into the...

curl: 41: `main_checkfds()` pipe reuse leaks proxy credentials into HTTPS upload body

Summary When curl is launched with stdin fd 0 and stderr fd 2 closed, maincheckfds in src/toolmain.c can assign opposite ends of the same pipe to fd 0 and fd 2. In verbose mode with a stdin-based upload through an authenticated proxy, the Proxy-Authorization header written to stderr becomes...

curl: 37: `curl_mprintf` `%F` format specifier not consumed, causing variadic argument desynchronization

Summary docs/libcurl/curlmprintf.md documents %F as a conversion that consumes a double, alongside %f. However, parseconversion in lib/mprintf.c has no F case — it falls through to the default branch and returns without assigning an input slot. In a sequential format like "%F%s", the %s conversio...

curl: 22: FTP wildcard matching decodes server-provided filenames, enabling directory traversal

Summary When CURLOPTWILDCARDMATCH is enabled, libcurl concatenates the server-provided LIST filename directly onto the wildcard path and then URL-decodes the combined string. A filename containing percent-encoded path separators e.g. %2e%2e%2fsecret.txt is decoded into ../secret.txt, causing...

curl: 18: Explicit IPv6 proxy zone ID silently ignored — proxy credentials sent to wrong interface

Explicit IPv6 proxy zone ID silently ignored — proxy credentials sent to wrong interface Summary When a proxy is configured with a literal link-local IPv6 address and an explicit zone ID e.g. http://fe80::1%25eth0:8080, curl parses and stores the zone correctly but never applies it to the socket...

curl: 11: `CURLOPT_FORBID_REUSE` silently lost on multiplexed HTTP/2 connection when the forbidding transfer finishes first

Summary When HTTP/2 transfers share a multiplexed connection, CURLOPTFORBIDREUSE set by a transfer that completes before the other active streams is silently discarded. The connection survives into the idle pool and can be reused by a subsequent transfer. This breaks the mitigation documented in...

curl: 08: CVE-2026-7009 fix incomplete for AWS-LC: `--cert-status` bypass on SecTrust path

Summary The fix for CVE-2026-7009 commit 51905671e0 does not cover AWS-LC. In osslappleverify in lib/vtls/openssl.c, a missing OCSP staple is detected only when SSLgettlsextstatusocspresp returns a negative length. OpenSSL returns -1 for absence, but AWS-LC returns 0 with a NULL output pointer. O...

curl: 07: GnuTLS 0-RTT early data bypasses file-backed public-key pin verification

GnuTLS 0-RTT early data bypasses file-backed public-key pin verification Summary When CURLSSLOPTEARLYDATA is enabled and CURLOPTPINNEDPUBLICKEY references a file path, replacing that file's contents between connections does not invalidate the TLS session cache. On the next connection, curl sends...

curl: 06: Incomplete fix for CVE-2026-7009: GCC/SecTrust builds silently discard stapled OCSP responses

Summary Curlvtlsappleverify in lib/vtls/apple.c passes the stapled OCSP response to SecTrustSetOCSPResponse only when both HAVEBUILTINAVAILABLE and SUPPORTSSecOCSP are defined. When HAVEBUILTINAVAILABLE is absent, the OCSP buffer is silently discarded. GCC does not support builtinavailable, so th...

curl: CVE-2026-82208: wolfSSL CA-cache hit overrides callback

Summary With the wolfSSL backend, when CA caching is enabled and an CURLOPTSSLCTXFUNCTION callback replaces the trust store, curl can silently reinstall the cached store after the callback returns. A certificate trusted by the cached store but rejected by the callback-selected store is then...

curl: CVE-2026-80255: secure cookie attribute bypass with tab

Summary A Set-Cookie header using HTAB horizontal tab instead of SPACE before the Secure attribute — e.g. Set-Cookie: sid=SECRET;\tSecure — causes curl to store the cookie without its Secure flag. The cookie is then sent over plaintext HTTP on subsequent requests to the same host. The...

curl: CVE-2026-82209: domain-scoped PSL domain cookie

Summary When libpsl is enabled and a response host is itself a public suffix e.g. github.io, a Set-Cookie header whose Domain attribute exactly equals that host is accepted by psliscookiedomainacceptable but stored with tailmatch = TRUE. RFC 6265 §5.3 requires this exact-match case to produce a...

curl: 12: SASL DIGEST-MD5 does not validate the server's `rspauth` proof

Summary curl never verifies the rspauth value the server sends during SASL DIGEST-MD5 authentication. In Curlsaslcontinue lib/curlsasl.c, the SASLDIGESTMD5RESP handler unconditionally sends an empty acknowledgment without reading or checking the server's continuation data. Authentication then...

curl: 10: CURLOPT_MAXLIFETIME_CONN bypass on active HTTP/2 connections

Summary CURLOPTMAXLIFETIMECONN is not enforced when a new transfer is attached to an active multiplexed HTTP/2 connection. The connection-age eligibility check in urlmatchconn is gated behind !CONNINUSEconn, so an in-use HTTP/2 connection with spare stream capacity is accepted without any age...

curl: 46: `--libcurl` output carries `--insecure` across `--next` boundaries

Summary When --libcurl generates C source for a command that uses --next to separate multiple operations, local options from earlier operations leak into later ones. Specifically, if the first operation uses --insecure and the second does not, the generated program silently skips TLS certificate...

curl: 43: HTTP proxy CONNECT header chooses the `-OJ` filename after a redirect

Summary When curl follows an HTTPS redirect through an HTTP CONNECT proxy, a stale response code lets the proxy's CONNECT response Content-Disposition header control the local output filename. With --location --remote-name --remote-header-name, the proxy-provided filename is used for the...

curl: 34: `curl_mprintf` reads `double` for documented `long double` conversions — uninitialized value disclosure

Summary docs/libcurl/curlmprintf.md documents that the L length modifier makes floating-point conversions %f, %e, %E, %g, %G accept a long double argument. The implementation in lib/mprintf.c recognizes L and sets FLAGSLONGDOUBLE, but the conversion switch %f/%e/%E/%g/%G unconditionally selects...

curl: 36: HTTP upload resume offset consumed twice after early 307/308 redirect

Summary A read-backed HTTP POST using CURLOPTRESUMEFROMLARGE with a non-seekable source silently uploads the wrong data when the server returns a 307 or 308 redirect before the request body is sent. curleasyperform returns CURLEOK, so the caller cannot detect the substitution. The bug is in...

curl: 33: CONNECT_ONLY raw I/O selects wrong connection after CURLOPT_SHARE detach (incomplete fix for CVE-2020-8231)

Summary After a completed CURLOPTCONNECTONLY transfer, detaching the shared connection pool via curleasysetopteasy, CURLOPTSHARE, NULL causes curleasysend / curleasyrecv to silently operate on an unrelated connection from a different pool. Data intended for server B is sent to server A, and A's...

curl: 27: IMAP custom FETCH listing classification skips literal boundaries, enabling response desynchronization

Summary iscustomfetchlistingmatch in lib/imap.c classifies any custom FETCH whose sequence set contains : or , as a "listing." For that classification, imapstatelistsearchresp skips literal detection entirely. The ping-pong line parser then scans the server-declared literal body as IMAP protocol...

curl: 29: CURLOPT_ISSUERCERT accepts a different-key certificate when issuer metadata collides

Summary osslcheckissuer in lib/vtls/openssl.c uses X509checkissued to implement CURLOPTISSUERCERT. This OpenSSL function checks metadata subject/issuer names, key identifiers, algorithm compatibility, key usage but does not verify the certificate's cryptographic signature. A certificate with...

curl: 28: HTTP/3 UDP path ignores CURL_SOCKOPT_ALREADY_CONNECTED, reconnects callback-provided socket

Summary When CURLOPTSOCKOPTFUNCTION returns CURLSOCKOPTALREADYCONNECTED, the HTTP/3 QUIC UDP code path ignores it and calls connect anyway, silently reassociating the application-provided socket to a different peer. The TCP path has the correct check. This violates the documented callback contrac...

curl: Heap-use-after-free in CURLOPT_REFERER when passed a CURLINFO_REFERER pointer

Summary Setting CURLOPTREFERER with a pointer previously obtained from CURLINFOREFERER on the same easy handle triggers a heap-use-after-free. The CURLOPTREFERER handler frees data-state.referer line lib/setopt.c:2089 before Curlsetstropt reads from the now-dangling pointer line...

curl: Stacked --proto modifiers leave denied protocol enabled

Summary proto2num line 431–447 consumes only one leading modifier character via a switch statement. The documentation says entries may be "prefixed by zero or more modifiers." Before commit 86ac471d, a loop consumed all modifiers. The replacement switch reads only the first character. --proto...

curl: --etag-save - truncates append-redirected stdout

Summary saveetag line 267–273 calls fileno, fstat, ftruncatefd, 0 whenever the underlying fd is a regular file. It does not check OutStruct.regularfile, which is FALSE for stdout even when shell-redirected to a file. When --etag-save - is used with append redirection , an HTTP 2xx/3xx response...

curl: CVE-2026-80256: wcurl backslash bypass

A vulnerability was discovered in the wcurl script of the curl project. The vulnerability allowed an attacker-controlled URL to create a new file outside the directory chosen by a Windows user, subject to the user's filesystem permissions and the target not already existing. The vulnerability was...