CVE-2026-53587
HIGHDescription
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.
How to fix
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 40% of all known CVEs.
References
Related Vulnerabilities
Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-3400 | Critical | 10.0 | 100% | KEV + Ransom | - |
| CVE-2021-45105 | Medium | 5.9 | 100% | - | Fix |
| CVE-2021-44228 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2021-21985 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2020-3452 | High | 7.5 | 100% | KEV | Fix |
| CVE-2018-7600 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2026-53587?
Published advisories record a fix for 60 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-53587 being actively exploited?
Not that we know of. CVE-2026-53587 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.47% is the estimated probability that it will be exploited in the next 30 days. That is higher than 40% of all scored CVEs.
How severe is CVE-2026-53587?
CVE-2026-53587 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-53587 affect?
Published advisories record a fix for libgit2 (Debian), cargo (Red Hat / RHEL), cargo (Rocky), cargo-debuginfo (Red Hat / RHEL), and 56 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-09.