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Fencer Intel
high 7.5

CVE-2026-105437 json

Heap-based Buffer Overflow in Git

published yesterday modified yesterday also EUVD-2026-122614

cvss
7.5
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 34%
public exploits
0
none known

Summary

Affected versions of Git have a heap buffer overflow in the three-way merge code (xdiff), which an attacker can trigger through a repository they control.

When Git merges a file, it first adds up the size of the merged output, allocates a buffer of that size, and then writes the output into it. That total was kept in a 32-bit signed integer. The conflict-marker-size attribute, which can be set from a committed .gitattributes file, accepts any positive integer, and the markers are written several times for every conflict. A small file with a huge marker size and many separate conflicts can therefore push the total past 4 GiB, so the integer wraps to a small value and Git writes attacker-controlled merge output past the end of a buffer that is too small. At minimum this crashes Git, and because the overflow is large and its contents are largely attacker-controlled, worse heap corruption is possible.

Any command that does a textual three-way merge can trigger it, such as git-merge(1), git-rebase(1), git-cherry-pick(1), and git-merge-tree(1). The latter is most likely a target for Git forges, which might use git-merge-tree(1) on the server-side to check mergeability. When the server reads attributes from trees in the repository (for example through attr.tree or --attr-source), any user who can push branches and request that they be merged (for example by opening a pull or merge request) can trigger the overflow without anyone else doing anything, and the data they push is small because the oversized output only appears during the merge.

The problem has been patched by computing the size as size_t and checking every addition for overflow, so Git stops with an error instead of overflowing.

Servers that cannot upgrade right away can add

* conflict-marker-size=7

to each repository's info/attributes as a workaround, which overrides any in-tree .gitattributes, or turn off server-side mergeability checks for untrusted repositories.

Patch / fix

  • Git Git 2.49.1, 2.50.2, 2.51.3, 2.52.1, 2.53.1, 2.54.1, 2.55.1, 2.56.1
  • git Alpine 3.23 2.52.1-r0
  • git Alpine 3.24 2.54.1-r0

alpine advisories ALPINE-CVE-2026-105437

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

Is CVE-2026-105437 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-105437 updated cvss 7.5

git: git: Heap corruption via integer overflow in merge size calculations

  • Red Hat Enterprise Linux 6 git, gitk, gitweb, git-all, git-cvs, git-gui, +6 more Red Hat Enterprise Linux 7 git, gitk, git-hg, git-p4, gitweb, git-all, +12 more Red Hat Enterprise Linux 8 git, gitk, gitweb, git-all, git-gui, git-svn, +8 more Red Hat Enterprise Linux 9 git, gitk, gitweb, git-all, git-gui, git-svn, +8 more Red Hat Enterprise Linux 10 git Red Hat Hardened Images git
    +5 more products
    Red Hat OpenShift AI (RHOAI) rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/pluginregistry-rhel9 Red Hat Satellite 6 rubygem-git
    affected: workaround, no fix available

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

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/4044249 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:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • Git Git

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

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