Vulnerability Database

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Total vulnerabilities in the database

CVE-2026-105437 — git-scm / git

Heap-based Buffer Overflow

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.

  • Published: Nov 10, 2026
  • Updated: Nov 13, 2026
  • CVE: CVE-2026-105437
  • Severity: High
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: High
  • Score: 7.5
  • AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CWEs:

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Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.