CVE-2026-53583

Name	CVE-2026-53583
Description	libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, verify_server_cert in src/libgit2/streams/openssl.c uses an inverted !!memcmp result in the GEN_IPADD branch when comparing an IP-literal host with a certificate IP SubjectAltName. OpenSSL builds reject matching IP addresses and accept mismatched IP addresses, allowing a network attacker with a CA-trusted certificate containing any IP SubjectAltName to intercept libgit2 connections to IP-literal HTTPS URLs. DNS SubjectAltName validation and non-OpenSSL TLS backends are not affected. This issue is fixed in versions 1.8.6 and 1.9.5.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DSA-6453-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libgit2 (PTS)	bullseye (security), bullseye	1.1.0+dfsg.1-4+deb11u2	vulnerable
	bookworm, bookworm (security)	1.5.1+ds-1+deb12u1	vulnerable
	trixie	1.9.0+ds-2	vulnerable
	trixie (security)	1.9.0+ds-2+deb13u1	fixed
	forky, sid	1.9.7+ds-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libgit2	source	trixie	1.9.0+ds-2+deb13u1		DSA-6453-1
libgit2	source	(unstable)	1.9.6+ds-1

Notes

https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp
Fixed by: https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f (v1.9.5)