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.
References7
- github.com/libgit2/libgit2/commit/0cdfdd5fa8f8514c82413025e1e08…
- github.com/libgit2/libgit2/commit/c1896f06df22cc0ca5658df3a8f6c…
- github.com/libgit2/libgit2/commit/dec22ac01ad9620c96b7b9ac3ef63…
- github.com/libgit2/libgit2/releases/tag/v1.8.6
- github.com/libgit2/libgit2/releases/tag/v1.9.5
- github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x…
- github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x…
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - EPSS — exploit probability
- 0% percentile: 34 · as of 10 November 2026
- CWE
- CWE-770
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.