CVE-2026-5545

NameCVE-2026-5545
Descriptionlibcurl 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 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 code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different credentials. An application that first uses Negotiate authentication to a server with `user1:password1` and then does another operation to the same server asking for any authentication method but for `user2:password2` (while the previous connection is still alive) - the second request gets confused and wrongly reuses the same connection and sends the new request over that connection thinking it uses a mix of user1's and user2's credentials when it is in fact still using the connection authenticated for user1...
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
curl (PTS)bullseye7.74.0-1.3+deb11u13vulnerable
bullseye (security)7.74.0-1.3+deb11u16vulnerable
bookworm7.88.1-10+deb12u14vulnerable
bookworm (security)7.88.1-10+deb12u5vulnerable
trixie8.14.1-2+deb13u3vulnerable
forky8.20.0-1fixed
sid8.20.0-2fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
curlsource(unstable)8.20.0~rc2-1

Notes

[trixie] - curl <no-dsa> (Minor issue)
[bookworm] - curl <no-dsa> (Minor issue)
[bullseye] - curl <postponed> (Minor issue; can be fixed in next update)
https://curl.se/docs/CVE-2026-5545.html
Introduced by: https://github.com/curl/curl/commit/e56ae1426cb7a0a4a427cf8d6099a821fdaae428 (curl-7_10_6)
Fixed by: https://github.com/curl/curl/commit/33e43985b8f3b9e66691d06e70be0395849856cd (rc-8_20_0-1)

Search for package or bug name: Reporting problems