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CVE-2026-105437

Heap-based Buffer Overflow in Git

No exploitation reported by the sources we read.

  • Published2026-11-10
  • WeaknessCWE-122

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-11-1018:34CVE publishedCNA

Versions per branch

Products declared by the CNA

As GitLab, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • Gitother versions: not affected

    https://gitlab.com/git-scm/git

    Affected
    • < 2.49.1fixed in 2.49.1semver
    • ≥ 2.50.0-rc0, < 2.50.2fixed in 2.50.2semver
    • ≥ 2.51.0-rc0, < 2.51.3fixed in 2.51.3semver
    • ≥ 2.52.0-rc0, < 2.52.1fixed in 2.52.1semver
    • ≥ 2.53.0-rc0, < 2.53.1fixed in 2.53.1semver
    • ≥ 2.54.0-rc0, < 2.54.1fixed in 2.54.1semver
    • ≥ 2.55.0-rc0, < 2.55.1fixed in 2.55.1semver
    • ≥ 2.56.0-rc0, < 2.56.1fixed in 2.56.1semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-10

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-105437 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.17.52026-11-10
  • CNAweakness (CWE)CWE-1222026-11-10
  • NVDweakness (CWE)CWE-122read 2026-11-10

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2026-11-10
Last Modified
2026-11-10
NVD status
Received

Frequently asked questions

What is CVE-2026-105437?

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.

Is CVE-2026-105437 actively exploited?

Active exploitation of CVE-2026-105437 has not been confirmed.

What is the CVSS score for CVE-2026-105437?

CVE-2026-105437 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H.

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