CVE-2026-53585
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.
CSIRTS triage
- What
- Multiple vulnerabilities allow arbitrary command execution on remote SSH servers, credential disclosure, denial of service, and directory creation outside the repository working tree.
- Who is affected
- All deployments of libgit2 using the affected functionality are at risk.
- Urgency
- Urgent; remote code execution on SSH servers is a critical security risk with active exploitation potential.
- Action
- Apply the security update DSA-6453-1 immediately.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 25% of all EPSS-scored CVEs.
Advisory coverage (3)
- mediumCVE-2026-53585: libgit2 is a portable C implementation of the Git core methods provided as a linkable library …nvd · 2026-08-20
- lowDSA-6453-1 libgit2 - security updatedebian · 2026-08-20
- unknownUSN-8628-1: libgit2 vulnerabilitiesubuntu · 2026-08-12
External references
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[](https://www.csirts.com/cve/CVE-2026-53585)