CVE-2026-53587
libgit2 - Unauthenticated network-reachable heap out-of-bounds read in transports/smart_pkt.c:set_data
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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, libgit2 performs a fixed-size strncmp in set_data in src/libgit2/transports/smart_pkt.c without first verifying that the smart-protocol pkt-line capability buffer contains 14 bytes. A malicious Git server can make bytes after the pkt-line complete object-format=, causing format_str to advance beyond the pkt-line and the following memchr length calculation to underflow. The resulting heap out-of-bounds walk can crash a client during the first refs-advertisement packet over HTTP, HTTPS, SSH, or the Git protocol. This issue is fixed in versions 1.8.6 and 1.9.5.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Awaiting Analysis | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.47% · top 59% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
- CWE-20: Improper Input Validation (opens in a new tab)All about CWE-20 and its CVEs
- CWE-125: Out-of-bounds Read (opens in a new tab)All about CWE-125 and its CVEs
- CWE-126: Buffer Over-read (opens in a new tab)All about CWE-126 and its CVEs
- CWE-1284: Improper Validation of Specified Quantity in Input (opens in a new tab)All about CWE-1284 and its CVEs
Affected products
References (6)
- https://github.com/libgit2/libgit2/security/advisories/GHSA-pm24-4jhq-3xvm (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/libgit2/libgit2/commit/2c0ce8c0132ac38ab0db28239462a671e2e5440e (opens in a new tab)x_refsource_MISC
- https://github.com/libgit2/libgit2/commit/affda60c10fcef16723451c0d7dc71b71dc20ad3 (opens in a new tab)x_refsource_MISC
- https://github.com/libgit2/libgit2/commit/d7a9fb87f504434e9f45228678953c4fa56e7640 (opens in a new tab)x_refsource_MISC
- https://github.com/libgit2/libgit2/releases/tag/v1.8.6 (opens in a new tab)x_refsource_MISC
- https://github.com/libgit2/libgit2/releases/tag/v1.9.5 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-53587)Record last updated .