High [CVE-2026-53587] Denial of Service due to heap out-of-bounds read from malicious Git server
This high-severity Red Hat Linux advisory covers CVE-2026-53587 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
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.
A flaw was found in libgit2. A fixed-size string comparison in the `set_data` function within `transports/smart_pkt.c` does not adequately verify the size of a network packet buffer.
A remote attacker, operating a malicious Git server, can send a specially crafted packet-line capability buffer. This can lead to a heap out-of-bounds read, causing the client application to crash and resulting in a Denial of Service (DoS).
Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-125.
- < 1.8.6
- < 1.9.5
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
- 1.8.6
- 1.9.5
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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