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.
Published: 2026-08-20
Score: 6.5 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

No analysis available yet.

Remediation

No remediation available yet.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DSA Debian DSA DSA-6453-1 libgit2 security update
History

Thu, 20 Aug 2026 20:45:00 +0000

Type Values Removed Values Added
First Time appeared Libgit2
Libgit2 libgit2
Vendors & Products Libgit2
Libgit2 libgit2

Thu, 20 Aug 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 20 Aug 2026 19:00:00 +0000

Type Values Removed Values Added
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.
Title libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend
Weaknesses CWE-295
CWE-297
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-20T19:04:42.247Z

Reserved: 2026-06-09T19:11:53.484Z

Link: CVE-2026-53583

cve-icon Vulnrichment

Updated: 2026-08-20T19:02:30.259Z

cve-icon NVD

Status : Received

Published: 2026-08-20T19:16:54.500

Modified: 2026-08-20T19:16:54.500

Link: CVE-2026-53583

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-20T20:30:05Z

Weaknesses
  • CWE-295

    Improper Certificate Validation

  • CWE-297

    Improper Validation of Certificate with Host Mismatch