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Fencer Vulns
medium 5.3

CVE-2026-53585 json

libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header

published 2026-08-20 2 mo ago modified 2026-10-26 13 d ago also EUVD-2026-63548 , JLSEC-2026-1371

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
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, git_delta_apply in src/libgit2/delta.c trusts the attacker-controlled res_sz value parsed by hdr_sz from a delta object header and passes that amount to git__malloc before validating delta instructions. Malicious pack data supplied through git_clone, git_fetch, git_remote_fetch, git_indexer_append, or a local attacker-supplied repository can use a very small multi-level OFS_DELTA chain to retain extremely large allocations and exhaust memory. 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 12 1.5.1+ds-1+deb12u2
  • libgit2 Debian 13 1.9.0+ds-2+deb13u1
  • libgit2 Debian 14 1.9.6+ds-1

debian advisories DEBIAN-CVE-2026-53585

  • libgit2 Ubuntu 24.04 LTS 1.7.2+ds-1ubuntu3.1
  • libgit2 Ubuntu 26.04 LTS 1.9.1+ds-1ubuntu1.1
  • libgit2 Ubuntu Pro 14.04 LTS 0.19.0-2ubuntu0.4+esm2
  • libgit2 Ubuntu Pro 16.04 LTS 0.24.1-2ubuntu0.2+esm3
  • libgit2 Ubuntu Pro 18.04 LTS 0.26.0+dfsg.1-1.1ubuntu0.2+esm2
  • libgit2 Ubuntu Pro 20.04 LTS 0.28.4+dfsg.1-2ubuntu0.1+esm1
  • libgit2 Ubuntu Pro 22.04 LTS 1.1.0+dfsg.1-4.1ubuntu0.1+esm1

ubuntu advisories UBUNTU-CVE-2026-53585

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

  • libgit2 hummingbird 1 1.9.7-1.hum1

red hat advisories RHSA-2026:59361

  • libgit2 openSUSE Tumbleweed 1.9.6-1.1

opensuse advisories openSUSE-SU-2026:11315-1

  • libgit2 Alpine 3.24, Alpine 3.23 1.9.6-r0

alpine advisories ALPINE-CVE-2026-53585

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-96965

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

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-2026-53585 updated cvss 6.5

libgit2: libgit2: Denial of Service via Unbounded Memory Allocation

  • Red Hat Enterprise Linux 8 libgit2 Red Hat Enterprise Linux 9 rust, cargo, clippy, rustfmt, rust-gdb, rust-src, +8 more Red Hat Enterprise Linux 10 rust Red Hat Enterprise Linux AI (RHEL AI) 3 rust, libgit2
    affected: workaround, no fix available “To mitigate this issue, avoid cloning or fetching from untrusted Git repositories. Restricting access to systems that perform Git operations on untrusted data can also reduce exposure.”
  • Red Hat Hardened Images libgit2 1.9.7-1.hum1
    fixed: vendor fix “To mitigate this issue, avoid cloning or fetching from untrusted Git repositories. Restricting access to systems that perform Git operations on untrusted data can also reduce exposure.” 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
2 mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x79j referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns 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.