libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-53583
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-20 19:16:54 UTC
Updated2026-08-20 19:16:54 UTC
Descriptionlibgit2 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

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

Problem Types: CWE-295 | CWE-297 | CWE-295 CWE-295: Improper Certificate Validation | CWE-297 CWE-297: Improper Validation of Certificate with Host Mismatch

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Libgit2 Libgit2 affected < 1.8.6 Not specified
CNA Libgit2 Libgit2 affected >= 1.9.0, < 1.9.5 Not specified

References

ReferenceSourceLinkTags
github.com/libgit2/libgit2/releases/tag/v1.8.6 [email protected] github.com
github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d [email protected] github.com
github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff [email protected] github.com
github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/libgit2/libgit2/releases/tag/v1.9.5 [email protected] github.com
github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f [email protected] github.com
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