CVE-2026-53587
libgit2 - Unauthenticated network-reachable heap out-of-bounds read in transports/smart_pkt.c:set_data
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.
| CWE | CWE-20 CWE-125 CWE-126 CWE-1284 |
| Vendor | libgit2 |
| Product | libgit2 |
| Published | Aug 20, 2026 |
| Last Updated | Aug 20, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H