What’s Vulnerable › Vulnerabilities

CVE-2026-53585: libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% 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-770

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, git_delta_apply in src/libgit2/delta.c trusts the attacker-controlled res_sz value parsed by hdr_sz from a delta object header and passes that amount to git__malloc before validating delta instructions. Malicious pack data supplied through git_clone, git_fetch, git_remote_fetch, git_indexer_append, or a local attacker-supplied repository can use a very small multi-level OFS_DELTA chain to retain extremely large allocations and exhaust memory. 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/0cdfdd5fa8f8514c82413025e1e0808866cf7c30
• https://github.com/libgit2/libgit2/commit/c1896f06df22cc0ca5658df3a8f6cd7ede4cd6ae
• https://github.com/libgit2/libgit2/commit/dec22ac01ad9620c96b7b9ac3ef636ea46d43bed
• 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-27m5-gxxh-x79j
• https://github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x79j

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