Curl

Curl's SMB implementation contains a use-after-free vulnerability that causes denial of service when processing consecutive requests to the same host, as the library incorrectly dereferences freed memory on subsequent connections. Public exploit code exists for this vulnerability affecting Curl installations. An attacker can crash Curl-based applications or services by triggering multiple SMB requests, though remote code execution is not possible due to the nature of the memory corruption.

curl's HTTP proxy connection reuse mechanism fails to validate credential changes, allowing an attacker to intercept or manipulate traffic by leveraging an existing proxy connection established with different authentication. This affects users whose applications reuse proxy connections across requests with varying credentials, enabling credential confusion attacks. Public exploit code exists for this vulnerability, though a patch is available.

OAuth2 bearer token leakage in curl and .NET occurs when HTTP redirects are followed to a second hostname that matches entries in the .netrc configuration file, allowing attackers to obtain valid authentication tokens for unintended hosts. Public exploit code exists for this vulnerability affecting curl and .NET applications that rely on OAuth2 authentication with automatic redirect handling. This medium-severity vulnerability (CVSS 5.3) requires network access but no user interaction, and patches are available from vendors.

libcurl incorrectly reuses authenticated connections when processing Negotiate authentication requests, allowing an attacker with valid credentials to access resources authenticated under different user accounts. An authenticated attacker can exploit this connection pooling logic error to bypass authentication checks by reusing an existing connection that was authenticated with different credentials. This affects libcurl implementations using Negotiate authentication where multiple users access the same server.

When doing SSH-based transfers using either SCP or SFTP, and setting the known_hosts file, libcurl could still mistakenly accept connecting to hosts *not present* in the specified file if they were added as recognized in the libssh *global* known_hosts file. [CVSS 5.3 MEDIUM]

When doing TLS related transfers with reused easy or multi handles and altering the `CURLSSLOPT_NO_PARTIALCHAIN` option, libcurl could accidentally reuse a CA store cached in memory for which the partial chain option was reversed. Contrary to the user's wishes and expectations. [CVSS 5.3 MEDIUM]

When an OAuth2 bearer token is used for an HTTP(S) 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. [CVSS 5.3 MEDIUM]

When doing multi-threaded LDAPS transfers (LDAP over TLS) with libcurl, changing TLS options in one thread would inadvertently change them globally and therefore possibly also affect other concurrently setup transfers. [CVSS 6.3 MEDIUM]

When using `CURLOPT_PINNEDPUBLICKEY` option with libcurl or `--pinnedpubkey` with the curl tool,curl should check the public key of the server certificate to verify the peer. [CVSS 5.9 MEDIUM]

curl's code for managing SSH connections when SFTP was done using the wolfSSH powered backend was flawed and missed host verification mechanisms. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.

1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

curl's websocket code did not update the 32 bit mask pattern for each new outgoing frame as the specification says. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Denial of Service vulnerability in libcurl's WebSocket implementation that allows a malicious server to send a specially crafted packet triggering an endless busy-loop, forcing applications to kill the affected thread or process to recover. This affects all libcurl versions with WebSocket support, with CVSS 7.5 (High) severity due to network-accessible attack vector requiring no authentication. The vulnerability has high real-world impact for any application using libcurl for WebSocket connections, though exploitation requires active malicious server control.

libcurl supports *pinning* of the server certificate public key for HTTPS transfers. Rated medium severity (CVSS 4.8), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.

libcurl accidentally skips the certificate verification for QUIC connections when connecting to a host specified as an IP address in the URL. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

When libcurl is asked to perform automatic gzip decompression of content-encoded HTTP responses with the `CURLOPT_ACCEPT_ENCODING` option, **using zlib 1.2.0.3 or older**, an attacker-controlled. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

A double-close vulnerability exists in libcurl when tearing down connection channels after threaded name resolution, causing the same eventfd file descriptor to be closed twice. This affects curl version 8.11.1 and various NetApp products that bundle libcurl, potentially leading to file descriptor confusion, limited information disclosure, and high availability impact. A public proof-of-concept exploit is available (HackerOne report 2954286), and the vulnerability has a notably high EPSS score of 6.37% (91st percentile), indicating elevated real-world exploitation likelihood.

When asked to use a `.netrc` file for credentials **and** to follow HTTP redirects, curl could leak the password used for the first host to the followed-to host under certain circumstances. Rated low severity (CVSS 3.4), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.