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CVE-2026-53587

libgit2 - Unauthenticated network-reachable heap out-of-bounds read in transports/smart_pkt.c:set_data

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.8.6, 1.9.5
1 proof of concept on GitHub
  • Exploitation: poc
  • Automatable: yes
  • Technical impact: partial

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. This issue is fixed in versions 1.8.6 and 1.9.5.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: poc · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • libgit2 libgit2

    fixed in 1.8.6; From 1.9.0 · fixed in 1.9.5

References 7

GitHub · libgit2/libgit2

GitHub · Alixploit22/CVE-2026-53587