CVE-2026-105437: Git heap buffer overflow in three-way merge code

CVE-2026-105437 · Severity: high · CVSS 7.5 · Published 2026-11-10

Git, the widely used source code management system, contains a heap buffer overflow vulnerability in its three-way merge functionality that can be triggered through a malicious repository. An attacker who can push branches to a Git forge and request merges can cause Git to crash or corrupt memory on the server, potentially leading to code execution or denial of service. The vulnerability is particularly dangerous for Git forges that use server-side merge operations to check if pull requests are mergeable.

Technologies: Git. Vendors: Git.

Quick answers

Is CVE-2026-105437 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-105437 being exploited in the wild.
How severe is CVE-2026-105437?
High severity, with a CVSS score of 7.5, published 10 November 2026.
Which products and versions are affected?
Git Git.
Is there a fix for CVE-2026-105437?
No fixed version is recorded yet. Servers unable to upgrade immediately can add conflict-marker-size=7 to each repository's info/attributes to override malicious .gitattributes settings, or disable server-side mergeability checks for untrusted repositories. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-105437 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-105437?
Check whether you run Git. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Servers unable to upgrade immediately can add conflict-marker-size=7 to each repository's info/attributes to override malicious .gitattributes settings, or disable server-side mergeability checks for untrusted repositories.

Technical details

The vulnerability exists in the xdiff three-way merge code where the total output size is stored in a 32-bit signed integer. An attacker can craft a repository with a large conflict-marker-size attribute (set in .gitattributes) combined with many conflicts to overflow this integer counter past 4 GiB, causing Git to allocate a too-small buffer and write attacker-controlled data past its bounds. Commands like git-merge, git-rebase, git-cherry-pick, and especially git-merge-tree are vulnerable; server-side merge operations checking mergeability are the primary attack surface.

Affected products

  • Git Git

Timeline

  • 2026-11-10: disclosed

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