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Fencer Intel
high 7.5

CVE-2026-53587 json

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

published 2mo ago modified 14d ago also EUVD-2026-63547 , JLSEC-2026-1373

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

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.

Patch / fix

  • julia LibGit2_jll 1.9.6+0
  • libgit2 libgit2 1.8.6, 1.9.5
  • libgit2 Debian 13 1.9.0+ds-2+deb13u1
  • libgit2 Debian 14 1.9.6+ds-1

debian advisories DEBIAN-CVE-2026-53587

  • libgit2 Ubuntu 24.04 LTS 1.7.2+ds-1ubuntu3.1
  • libgit2 Ubuntu 26.04 LTS 1.9.1+ds-1ubuntu1.1

ubuntu advisories UBUNTU-CVE-2026-53587

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rust RHEL 10.2 1.92.0-2.el10_2
  • cargo RHEL 10.2 1.92.0-2.el10_2
  • clippy RHEL 10.2 1.92.0-2.el10_2
  • rustfmt RHEL 10.2 1.92.0-2.el10_2
  • rust-gdb RHEL 10.2 1.92.0-2.el10_2
  • rust-src RHEL 10.2 1.92.0-2.el10_2
  • rust-lldb RHEL 10.2 1.92.0-2.el10_2
  • rust-toolset RHEL 10.2 1.92.0-2.el10_2

red hat advisories RHSA-2026:69109RHSA-2026:69097RHSA-2026:69096RHSA-2026:67286RHSA-2026:67285RHSA-2026:59361

  • libgit2 openSUSE Tumbleweed 1.9.6-1.1

opensuse advisories openSUSE-SU-2026:11315-1

  • rust AlmaLinux 9 1.92.0-2.el9_8
  • cargo AlmaLinux 9 1.92.0-2.el9_8
  • clippy AlmaLinux 9 1.92.0-2.el9_8
  • rustfmt AlmaLinux 9 1.92.0-2.el9_8
  • rust-gdb AlmaLinux 9 1.92.0-2.el9_8
  • rust-src AlmaLinux 9 1.92.0-2.el9_8
  • rust-lldb AlmaLinux 9 1.92.0-2.el9_8
  • rust-toolset AlmaLinux 9 1.92.0-2.el9_8

almalinux advisories ALSA-2026:67285ALSA-2026:67286

  • rust Rocky Linux 9 1.92.0-2.el9_8
  • rust Rocky Linux 10 1.92.0-2.el10_2

rocky linux advisories RLSA-2026:67285RLSA-2026:67286

  • libgit2 Alpine 3.24, Alpine 3.23 1.9.6-r0

alpine advisories ALPINE-CVE-2026-53587

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libgit2 Azure Linux 3.0 1.7.2-3

azure linux advisories AZL-96968

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Is CVE-2026-53587 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-53587 updated cvss 7.5

libgit2: libgit2: Denial of Service due to heap out-of-bounds read from malicious Git server

  • Red Hat Enterprise Linux 8 libgit2 Red Hat Enterprise Linux AI (RHEL AI) 3 rust, libgit2
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rust 1.92.0-2.el9_8, cargo 1.92.0-2.el9_8, clippy 1.92.0-2.el9_8, rustfmt 1.92.0-2.el9_8, rust-gdb 1.92.0-2.el9_8, rust-src 1.92.0-2.el9_8, +6 more
    fixed: vendor fix RHSA-2026:67285
  • Red Hat Enterprise Linux AppStream (v. 10) rust 1.92.0-2.el10_2, cargo 1.92.0-2.el10_2, clippy 1.92.0-2.el10_2, rustfmt 1.92.0-2.el10_2, rust-gdb 1.92.0-2.el10_2, rust-src 1.92.0-2.el10_2, +7 more
    fixed: vendor fix RHSA-2026:67286
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rust 1.75.0-1.el9_4.1, cargo 1.75.0-1.el9_4.1, clippy 1.75.0-1.el9_4.1, rustfmt 1.75.0-1.el9_4.1, rust-gdb 1.75.0-1.el9_4.1, rust-src 1.75.0-1.el9_4.1, +6 more
    fixed: vendor fix RHSA-2026:69097
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rust 1.84.1-1.el10_0.4, cargo 1.84.1-1.el10_0.4, clippy 1.84.1-1.el10_0.4, rustfmt 1.84.1-1.el10_0.4, rust-gdb 1.84.1-1.el10_0.4, rust-src 1.84.1-1.el10_0.4, +7 more
    fixed: vendor fix RHSA-2026:69096
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rust 1.84.1-1.el9_6.1, cargo 1.84.1-1.el9_6.1, clippy 1.84.1-1.el9_6.1, rustfmt 1.84.1-1.el9_6.1, rust-gdb 1.84.1-1.el9_6.1, rust-src 1.84.1-1.el9_6.1, +6 more
    fixed: vendor fix RHSA-2026:69109
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) rust-std-static-x86_64-unknown-none 1.92.0-2.el10_2, rust-std-static-aarch64-unknown-none-softfloat 1.92.0-2.el10_2
    fixed: vendor fix RHSA-2026:67286
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) rust-std-static-x86_64-unknown-none 1.84.1-1.el10_0.4, rust-std-static-aarch64-unknown-none-softfloat 1.84.1-1.el10_0.4
    fixed: vendor fix RHSA-2026:69096
show 1 more
  • Red Hat Hardened Images libgit2 1.9.7-1.hum1
    fixed: vendor fix RHSA-2026:59361

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/libgit2/libgit2/security/advisories/GHSA-pm24-4jhq-3xvm referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia LibGit2_jll
<1.9.6+0
1.9.6+0

Affected products

  • libgit2 libgit2

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-125 Out-of-bounds Read
  • CWE-126 Buffer Over-read
  • CWE-1284 Improper Validation of Specified Quantity in Input

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.