CURL-CVE-2016-0754 remote filename path traversal in curl tool for Windows

curl does not sanitize colons in a remote filename that is used as the local filename. This may lead to a vulnerability on systems where the colon is a special path character. Currently Windows is the only OS where this vulnerability applies. curl offers command line options --remote-name also...

CURL-CVE-2025-10148 predictable WebSocket mask

curl's WebSocket code did not update the 32-bit mask pattern for each new outgoing frame as the specification says. Instead it used a fixed mask that persisted and was used throughout the entire connection. A predictable mask pattern allows for a malicious server to induce traffic between the two...

CURL-CVE-2026-8924 trailing dot domain super cookie

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set "super cookies" that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains...

CURL-CVE-2026-5545 wrong reuse of HTTP Negotiate connection

libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTPS request after a Negotiate-authenticated one, when both use the same host. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid...

CURL-CVE-2022-27776 Auth/cookie leak on redirect

curl might leak authentication or cookie header data on HTTP redirects to the same host but another port number. When asked to send custom headers or cookies in its HTTP requests, curl sends that set of headers only to the host which name is used in the initial URL, so that redirects to other hos...

CURL-CVE-2016-8617 OOB write via unchecked multiplication

In libcurl's base64 encode function, the output buffer is allocated as follows without any checks on insize: malloc insize 4 / 3 + 4 On systems with 32-bit addresses in userspace e.g. x86, ARM, x32, the multiplication in the expression wraps around if insize is at least 1GB of data. If this...

CURL-CVE-2026-8927 env-set cross-proxy Digest auth state leak

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against proxyA using Digest auth, a subsequent transfer routed...

CURL-CVE-2023-27537 HSTS double free

libcurl supports sharing HSTS data between separate "handles". This sharing was introduced without considerations for doing this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS...

CURL-CVE-2026-5773 wrong reuse of SMB connection

libcurl might in some circumstances reuse the wrong connection for SMBS transfers. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the...

CURL-CVE-2023-27538 SSH connection too eager reuse still

libcurl would reuse a previously created connection even when an SSH related option had been changed that should have prohibited reuse. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, two SSH settings were...

CURL-CVE-2012-0036 URL sanitization vulnerability

curl is vulnerable to a data injection attack for certain protocols through control characters embedded or percent-encoded in URLs. When parsing URLs, libcurl's parser is liberal and only parses as little as possible and lets as much as possible through as long as it can figure out what to do. In...

CURL-CVE-2026-9080 UAF after pause in socket callback

Calling curleasypause within the event-based CURLMOPTSOCKETFUNCTION callback triggers a use-after-free vulnerability, where libcurl attempts to store a flag using a dangling struct pointer immediately after that pointer's memory has been freed...

CURL-CVE-2020-8285 FTP wildcard stack overflow

libcurl offers a wildcard matching functionality, which allows a callback set with CURLOPTCHUNKBGNFUNCTION to return information back to libcurl on how to handle a specific entry in a directory when libcurl iterates over a list of all available entries. When this callback returns...

CURL-CVE-2019-3823 SMTP end-of-response out-of-bounds read

libcurl contains a heap out-of-bounds read in the code handling the end-of-response for SMTP. If the buffer passed to smtpendofresp is not null-terminated and contains no character ending the parsed number, and len is set to 5, then the strtol call reads beyond the allocated buffer. The read...

CURL-CVE-2018-1000005 HTTP/2 trailer out-of-bounds read

libcurl contains an out bounds read in code handling HTTP/2 trailers. It was reported that reading an HTTP/2 trailer could mess up future trailers since the stored size was one byte less than required. The problem is that the code that creates HTTP/1-like headers from the HTTP/2 trailer data once...

CURL-CVE-2017-8818 SSL out of buffer access

libcurl contains an out boundary access flaw in SSL related code. When allocating memory for a connection the internal struct called connectdata, a certain amount of memory is allocated at the end of the struct to be used for SSL related structs. Those structs are used by the particular SSL libra...

CURL-CVE-2026-80255 secure cookie attribute bypass with tab

A Set-Cookie: header using tab horizontal tab, ASCII code 9 instead of space ascii code 32 immediately before the Secure attribute causes curl to store the cookie without its Secure flag. The cookie might then wrongfully be sent over plaintext HTTP on subsequent requests to the same host...

CURL-CVE-2026-11564 Native CA trust persist

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. An easy handle that first uses default native CA trust can continue trusting the native platform store after the application switches that same handle to custom CA...

CURL-CVE-2026-12064 proto-default skips SSH verification

When a user invokes curl using a schemeless URL combined with --proto-default sftp or scp, a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like...

CURL-CVE-2025-15224 libssh key passphrase bypass without agent set

When doing SSH-based transfers using either SCP or SFTP, and asked to do public key authentication, curl would wrongly still ask and authenticate using a locally running SSH agent...

CURL-CVE-2025-14524 bearer token leak on cross-protocol redirect

When an OAuth2 bearer token is used for an HTTPS transfer, and that transfer performs a cross-protocol redirect to a second URL that uses an IMAP, LDAP, POP3 or SMTP scheme, curl might wrongly pass on the bearer token to the new target host...

CURL-CVE-2025-0725 gzip integer overflow

When libcurl is asked to perform automatic gzip decompression of content-encoded HTTP responses with the CURLOPTACCEPTENCODING option, using zlib 1.2.0.3 or older, an attacker-controlled integer overflow would make libcurl perform a buffer overflow...

CURL-CVE-2011-3389 SSL CBC IV vulnerability

curl is vulnerable to a SSL CBC IV vulnerability when built to use OpenSSL for the SSL/TLS layer. This vulnerability has been identified CVE-2011-3389 aka the "BEAST" attack and is addressed by OpenSSL already as they have made a workaround to mitigate the problem. When doing so, they figured out...

CURL-CVE-2000-0973 FTP Server Response Buffer Overflow

When storing an FTP server's error message on failure, there was no check for input length and thus a malicious FTP server could overflow curl's stack based buffer...

CURL-CVE-2018-1000007 HTTP authentication leak in redirects

curl might leak authentication data to third parties. When asked to send custom headers in its HTTP requests, curl sends that set of headers first to the host in the initial URL but also, if asked to follow redirects and a 30X HTTP response code is returned, to the host mentioned in URL in the...

CURL-CVE-2017-1000101 URL globbing out of bounds read

curl supports "globbing" of URLs, in which a user can pass a numerical range to have the tool iterate over those numbers to do a sequence of transfers. In the globbing function that parses the numerical range, there was an omission that made curl read a byte beyond the end of the URL if given a...

CURL-CVE-2014-0138 wrong reuse of connections

libcurl can in some circumstances reuse the wrong connection when asked to do transfers using other protocols than HTTP and FTP. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of...

CURL-CVE-2026-82208 wolfSSL CA-cache hit overrides callback

With the wolfSSL backend, when CA caching is enabled and an CURLOPTSSLCTXFUNCTION callback replaces the trust store, libcurl 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 incorrectl...

CURL-CVE-2026-6253 proxy credentials leak over redirect-to proxy

curl might erroneously pass on credentials for a first proxy to a second proxy. This can happen when the following conditions are true: 1. curl is setup to use specific different proxies for different URL schemes 2. the first proxy needs credentials 3. the second proxy uses no credentials 4. whil...

CURL-CVE-2026-4873 connection reuse ignores TLS requirement

A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text via IMAP, SMTP, or POP3, a subsequent request to that same host bypasses the TLS requirement and instead transm...

CURL-CVE-2022-27778 curl removes wrong file on error

curl might remove the wrong file when --no-clobber is used together with --remove-on-error. The --remove-on-error option tells curl to remove the output file when it returns an error, and not leave a partial file behind. The --no-clobber option prevents curl from overwriting a file if it already...

CURL-CVE-2022-27780 percent-encoded path separator in URL host

The curl URL parser wrongly accepts percent-encoded URL separators like '/' when decoding the hostname part of a URL, making it a different URL using the wrong hostname when it is later retrieved. For example, a URL like http://example.com%2F10.0.0.1/, would be allowed by the parser and get...

CURL-CVE-2021-22922 Wrong content via Metalink not discarded

When curl is instructed to download content using the Metalink feature, the contents is verified against a hash provided in the Metalink XML file. The Metalink XML file points out to the client how to get the same content from a set of different URLs, potentially hosted by different servers and t...

CURL-CVE-2021-22923 Metalink download sends credentials

When curl is instructed to get content using the Metalink feature, and a user name and password are used to download the Metalink XML file, those same credentials are then subsequently passed on to each of the servers from which curl downloads or tries to download the contents from. Often contrar...

CURL-CVE-2021-22898 TELNET stack contents disclosure

curl supports the -t command line option, known as CURLOPTTELNETOPTIONS in libcurl. This rarely used option is used to send variable=content pairs to TELNET servers. Due to flaw in the option parser for sending NEWENV variables, libcurl could be made to pass on uninitialized data from a stack bas...

CURL-CVE-2018-16839 SASL password overflow via integer overflow

libcurl contains a buffer overrun in the SASL authentication code. The internal function Curlauthcreateplainmessage fails to correctly verify that the passed in lengths for name and password are not too long, then calculates a buffer size to allocate. On systems with a 32-bit sizet, the math to...

CURL-CVE-2016-9953 Win CE Schannel cert name out of buffer read

curl's TLS server certificate checks are flawed on Windows CE. This vulnerability occurs in the verify certificate function when comparing a wildcard certificate name as returned by the Windows API function CertGetNameString to the hostname used to make the connection to the server. The pattern...

CURL-CVE-2014-3707 duphandle read out of bounds

libcurl's function curleasyduphandle has a bug that can lead to libcurl eventually sending off sensitive data that was not intended for sending. When doing an HTTP POST transfer with libcurl, you can use the CURLOPTCOPYPOSTFIELDS option to specify a memory area holding the data to send to the...

CURL-CVE-2014-0015 reuse of wrong HTTP NTLM connection

libcurl can in some circumstances reuse the wrong connection when asked to do an NTLM-authenticated HTTP or HTTPS request. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criterion...

CURL-CVE-2026-11856 cross-origin Digest auth state leak

Successfully using libcurl to do a transfer to a specific HTTP origin hostA with Digest authentication and then changing the origin to a different one hostB for a second transfer, reusing the same handle, makes libcurl wrongly pass on the Authorization: header field meant for hostA, to hostB...

CURL-CVE-2026-7009 OCSP stapling bypass with Apple SecTrust

When curl is told to use the Certificate Status Request TLS extension, often referred to as OCSP stapling, to verify that the server certificate is valid, it fails to detect OCSP problems and instead wrongly consider the response as fine...

CURL-CVE-2026-3805 use after free in SMB connection reuse

When doing a second SMB request to the same host again, curl would wrongly use a data pointer pointing into already freed memory...

CURL-CVE-2022-27781 CERTINFO never-ending busy-loop

libcurl provides the CURLOPTCERTINFO option to allow applications to request details to be returned about a TLS server's certificate chain. Due to an erroneous function, a malicious server could make libcurl built with NSS get stuck in a never-ending busy-loop when trying to retrieve that...

CURL-CVE-2021-22925 TELNET stack contents disclosure again

curl supports the -t command line option, known as CURLOPTTELNETOPTIONS in libcurl. This rarely used option is used to send variable=content pairs to TELNET servers. Due to flaw in the option parser for sending NEWENV variables, libcurl could be made to pass on uninitialized data from a stack bas...

CURL-CVE-2019-5443 Windows OpenSSL engine code injection

A non-privileged user or program can put code and a config file in a known non-privileged path under C:/usr/local/ that makes curl automatically run the code as an OpenSSL "engine" on invocation. If that curl is invoked by a privileged user it can do anything it wants. This flaw exists in the...

CURL-CVE-2019-5436 TFTP receive buffer overflow

libcurl contains a heap buffer overflow in the function tftpreceivepacket that receives data from a TFTP server. It calls recvfrom with the default size for the buffer rather than with the size that was used to allocate it. Thus, the content that might overwrite the heap memory is entirely...

CURL-CVE-2019-5435 Integer overflows in URL parser

libcurl contains two integer overflows in the curlurlset function that if triggered, can lead to a too small buffer allocation and a subsequent heap buffer overflow. The flaws only exist on 32-bit architectures and require excessive string input lengths...

CURL-CVE-2018-14618 NTLM password overflow via integer overflow

libcurl contains a buffer overrun in the NTLM authentication code. The internal function Curlntlmcoremknthash multiplies the length of the password by two SUM to figure out how large temporary storage area to allocate from the heap. The length value is then subsequently used to iterate over the...

CURL-CVE-2016-9594 uninitialized random

libcurl's new internal function that returns a good 32-bit random value was implemented poorly and overwrote the pointer instead of writing the value into the buffer the pointer pointed to. This random value is used to generate nonces for Digest and NTLM authentication, for generating boundary...

CURL-CVE-2014-8150 URL request injection

When libcurl sends a request to a server via an HTTP proxy, it copies the entire URL into the request and sends if off. If the given URL contains line feeds and carriage returns those are sent along to the proxy too, which allows the program to for example send a separate HTTP request injected...