What’s Vulnerable › Vulnerabilities

CVE-2026-53583: libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-26
• Weakness: CWE-295

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.

Affected products

• libgit2: before 1.8.6; from 1.9.0, < 1.9.5

References

• https://github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d
• https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f
• https://github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff
• https://github.com/libgit2/libgit2/releases/tag/v1.8.6
• https://github.com/libgit2/libgit2/releases/tag/v1.9.5
• https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp
• https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp

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