CVE-2026-53583

medium

Assigned by CNA: github_m

Published 2026-08-20 · Modified 2026-08-20

Discuss on Community Propose mitigation

CVSS v3

6.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v4 NEW

—

not yet in upstream

VIR risk

6.5

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.

Predictions

Exploit likelihood

75%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

Debian Mixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`1.9.0+ds-2+deb13u1`
sid	Fixed	`1.9.6+ds-1`
forky	Fixed	`1.9.6+ds-1`
bullseye	Affected	—
bookworm	Affected	—

References

CWEs

CWE-295 CWE-297

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.