# CVE-2026-53583

## Summary

- **CVE ID:** CVE-2026-53583
- **Severity:** MEDIUM
- **CVSS Score:** 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N)
- **CWE:** CWE-295, CWE-297
- **Published:** Aug 20, 2026
- **Last Modified:** Aug 20, 2026

## 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 — libgit2 (< 1.8.6)
- libgit2 — libgit2 (>= 1.9.0, < 1.9.5)

## References

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

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.19%
- **EPSS Percentile:** 8.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._