99 results · Feed
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High 8.1
local interface connection reuse mixup
When `CURLOPT_INTERFACE` (or the command line tool's `--interface` option) is set with one of the documented prefixes (`if!`, `host!`, `ifhost!`), that binding is not part of the connection reuse key, so a later transfer asking for a different source can sile…
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High 8.1
info leak uploading over WebSockets with GnuTLS
When curl is built with GnuTLS, a malicious WebSocket server can make curl send memory past its send buffer. This is due to an out of bounds read following when `gnutls_record_send()` returns a number of bytes sent **greater than the number of bytes it was gi…
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High 7.5
password leak in CURLINFO_EFFECTIVE_URL
libcurl could accidentally return a URL for `curl_easy_getinfo()`'s `CURLINFO_EFFECTIVE_URL` option containing credentials, even though neither the URL provided to libcurl nor the redirected URL did.
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High 7.5
curl_mime_free stack overflow by recursion
A deeply nested multipart MIME structure constructed via the public API causes a stack overflow in libcurl during normal cleanup operations. An excessive recursion depth within `curl_mime_free` leads to unbounded stack frame allocation during structure traver…
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High 7.5
-J no-clobber guarantee bypassed with 103 early hints
When invoked with `--remote-header-name` (`-J`), curl fails to preserve its documented anti-clobbering protection if an intermediate 103 Early Hints response precedes the final HTTP response, or if an `ETag` header is processed before `Content-Disposition` un…
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High 8.1
TFTP direction confusion
libcurl's TFTP state machine fails to validate state transitions against the requested transfer direction, accepting opening server responses for both reads and writes interchangeably. A malicious TFTP server can respond to a download request in a way that fo…
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Critical 9.1
FTP wildcard write callback mixup
When an FTP wildcard `LIST` operation fails, libcurl omits the restoration path meant for successful listings, leaving the write callback set to the internal listing parser and the write callback data pointing directly to the easy handle. Subsequent reuse of …
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High 8.1
never-ending loop via server response omission
By permanently omitting the final control-response line, a malicious FTP, IMAP, POP3, or SMTP server can exploit libcurl and completely bypass its configured transfer timeout mechanism, indefinitely blocking all concurrent transfers bound to the same multi-ha…
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High 8.1
server-set cookie aborts cookie jar load
When writing a long cookie name and value to a Netscape cookie jar, a remote HTTP server can make `curl` write a record that exceeds its line-length parsing limit. Consequently, any subsequent `curl` invocation reading from that same cookie jar using `--cooki…
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Critical 9.1
wolfSSL public-key pinning bypass
When built with wolfSSL, curl can successfully validate a pinned public key hash against a key the TLS peer does not possess. During the TLS handshake, wolfSSL validates the connection, but curl's subsequent re-parsing of the same certificate - tricked by a m…
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High 7.4
knownhost callback mismatches key as missing
When libcurl uses libssh2 with a hashed `known_hosts` file, an unrelated initial entry can cause host key validation to report a key *mismatch* as a *missing* key to the `CURLOPT_SSH_KEYFUNCTION` callback.
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High 8.1
HSTS response erases persisted entries
An authenticated HTTPS origin can supply an HSTS `max-age` value that the parser accepts, but time serialization later fails to process. On 64-bit systems, extreme max-age values compute an absolute expiry within standard time integer limits that exceeds cale…
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High 8.1
IMAP APPEND plus CRLF conversion command injection
Enabling `CURLOPT_CRLF` causes curl to advertise the raw input byte count in the `IMAP APPEND {N}` literal while transmitting line-ending expanded data. The server reads only $N$ bytes for the payload, causing the remaining overflow bytes to be interpreted an…
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High 8.1
HSTS cache import drops longer-lived child
Importing a `includeSubDomains` parent HSTS entry before a longer-lived child entry, silently drops the child. Consequently, when the parent expires, the child's valid HSTS policy is lost, causing curl to issue unencrypted HTTP requests rather than upgrading …
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Critical 9.1
leaking host credentials to HTTP proxy
An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:…
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High 8.1
redirect to SFTP or SCP bypasses host verification
A flaw in the curl command line tool's logic makes it only set SSH host verification options when interacting directly using SFTP or SCP, and not as a result of following a redirect.
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High 8.1
stale SigV4 headers sent unintended
Setting `CURLOPT_AWS_SIGV4` to NULL but does not disable SigV4 authentication, contrary to expectations and documentation. A subsequent transfer on the same handle still sends an `Authorization: AWS4-HMAC-SHA256` header to whatever URL isset next, leaking sta…
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High 8.2
domain-scoped PSL domain cookie
When libpsl support is enabled, libcurl fails to enforce the Public Suffix List boundary check when processing a `Set-Cookie` header where the `Domain` attribute explicitly matches an origin host that is itself a public suffix (e.g., `Domain=co.uk` set by `co…
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High 7.5
wolfSSL CA-cache hit overrides callback
With the wolfSSL backend, when CA caching is enabled and an `CURLOPT_SSL_CTX_FUNCTION` 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…
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High 7.5
native CA store conn reuse
A flaw in libcurl makes it wrongly reuse an existing HTTPS connection setup for a given hostname even when using a different Native CA Store setting (`CURLSSLOPT_NATIVE_CA`) than when the connection was created.
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High 7.5
OpenSSL pinning bypass
When `CURLOPT_PINNEDPUBLICKEY` is configured alongside options that disable standard peer verification (`CURLOPT_SSL_VERIFYPEER = 0` and `CURLOPT_SSL_VERIFYHOST = 0`), libcurl fails to enforce public key pinning on connections established without a presented …
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Critical 9.8
Negotiate ambient user conn reuse
A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, when the initial request is done using empty credentials. This can make user B's request get sent over user A's previously authenticated con…
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Critical 9.1
HTTP/2 server push UAF
A flaw in libcurl's handling of HTTP/2 Server Push streams, when the parent handle is set to share connections with other handles, can lead to use-after-free in the cleanup process.
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High 7.4
OpenLDAP SASL authentication bypass
A flaw in the libcurl SASL negotiation for LDAP authentication allows an incomplete handshake sequence to be misinterpreted as a successful cryptographic verification. An attacker executing a Man-in-the-Middle (MITM) attack can inject a premature or shortcut …
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Critical 9.8
stale proxy password leak
libcurl had a flaw that when instructed to clear proxy authentication credentials which made it not do so, leaving the old credentials around to get used for subsequent transfers that should not know nor use them.
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High 7.5CVE-2026-8932 Public exploit
incomplete mTLS config matching in conn reuse
libcurl would reuse a previously created connection even when some mTLS config 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 m…
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Critical 9.1
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 Diges…
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Critical 9.1
password leak with netrc and user in URL
When asking curl to use a `.netrc` file to find credentials and at the same time specifying a URL with a username (without a password), like `https://user@example.com/`, curl could wrongly get and use the password for *another* user set in the `.netrc` file f…
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Medium 6.5
wrong reuse for different services
libcurl might in some circumstances reuse the wrong connection when asked to do Negotiate-authenticated ones, even when they are set to use different "services". libcurl features a pool of recent connections so that subsequent requests can reuse an existing c…
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High 8.1
wrong STARTTLS connection reuse
A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.
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High 7.5
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 …
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Critical 9.8
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 `Authori…
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Critical 9.8
HTTP/2 stream-dependency tree UAF
A use-after-free vulnerability exists in libcurl when an application configures an HTTP/2 stream-dependency tree via `CURLOPT_STREAM_DEPENDS` or `CURLOPT_STREAM_DEPENDS_E`, subsequently invokes `curl_easy_reset()`, and finally terminates the handle with `curl…
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Medium 5.3
cross-proxy Digest auth state leak
Successfully using libcurl to do a transfer over a specific HTTP proxy (`proxyA`) with **Digest** authentication and then changing the proxy host to a second one (`proxyB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Pro…
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Medium 5.3
netrc credential leak with reused proxy connection
When asked to both use a `.netrc` file for credentials and to follow HTTP redirects, libcurl could leak the password used for the first host to the followed-to host under certain circumstances.
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High 7.5
stale custom cookie host causes cookie leak
Using libcurl, when a custom `Host:` header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom `Host:` header set, the second request would use stale information and pass on cookies m…
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Medium 5.9
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 se…
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Medium 6.5
wrong reuse of HTTP Negotiate connection
libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) request after a Negotiate-authenticated one, when both use the same host. libcurl features a pool of recent connections so that subsequent requests can re…
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Medium 5.9
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 bypasse…
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Medium 6.5
wrong proxy connection reuse with credentials
curl would wrongly reuse an existing HTTP proxy connection doing CONNECT to a server, even if the new request uses different credentials for the HTTP proxy. The proper behavior is to create or use a separate connection.