Last updated 25 September 2026
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.
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 response that bypasses complete peer validation.
Accessibility. This issue was addressed through improved state management.
Accessibility. This issue was addressed through improved state management.
A path traversal vulnerability exists in curl <8.0.0 SFTP implementation causes the tilde (~) character to be wrongly replaced when used as a prefix in the first path element in addition to its intended use as the first element to indicate a path relative to the user's home directory. Attackers can exploit this flaw to bypass filtering or execute arbitrary code by crafting a path like /~2/foo while accessing a server with a specific user.
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.
Last updated 25 September 2026
domain-scoped PSL domain cookie
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 (CURLSSLOPTNATIVECA) than when the connection was created.
Last updated 2 July 2026
A vulnerability in libcurl caused the HTTP Referer: header to persist even when explicitly cleared. While the documentation states that passing NULL to CURLOPTREFERER suppresses the header, the option failed to clear the internal state. As a result, the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.
Last updated 2 July 2026
In this scenario, libcurl first uses a proper HTTP/3 server for the initial transfers, and when it makes a second transfer to the same site it has been replaced by the attacker's impostor machine - without a valid certificate.
When libcurl returns to the hostname the second time with a cached SSL session (CURLOPTSSLSESSIONIDCACHE is not disabled) and early data enabled (the CURLSSLOPTEARLYDATA bit is set in CURLOPTSSLOPTIONS), libcurl might send off the second request's bytes on that new connection before enforcing the certificate verification failure. Potentially leaking sensitive information.
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.
env-set cross-proxy Digest auth state leak
incomplete mTLS config matching in conn reuse
Last updated 2 July 2026
Last updated 2 July 2026
Last updated 2 July 2026
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.
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.
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 incorrectly accepted.
netrc credential leak with reused proxy connection
stale custom cookie host causes cookie leak
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. while using the first proxy (using say http://), curl is asked to follow a redirect to a URL using another scheme (say https://), accessed using a second, different, proxy
cross-proxy Digest auth state leak
Last updated 10 July 2026
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 transmit data unencrypted.
Last updated 10 July 2026