SB2026101312 - Ubuntu update for libgit2

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Main Vulnerability Database SB2026101312

SB2026101312 - Ubuntu update for libgit2

Published: October 13, 2026

Security Bulletin ID SB2026101312
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper validation of certificate with host mismatch (CVE-ID: CVE-2026-53583)

CWE-ID: CWE-297 - Improper Validation of Certificate with Host Mismatch

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to bypass certificate hostname validation and perform a man-in-the-middle attack.

The vulnerability exists due to improper validation of a certificate with host mismatch in the verify_server_cert() function in src/libgit2/streams/openssl.c when verifying IP SubjectAltName entries for IP-literal HTTPS URLs. A remote attacker can present a valid CA-signed certificate containing any IP SAN to bypass certificate hostname validation and perform a man-in-the-middle attack.

Only libgit2 builds using the OpenSSL backend are affected, and exploitation requires connections to IP-literal HTTPS URLs rather than domain-name URLs.


Remediation

Install update from vendor's website.

References