# GitLab Patches Heap Overflow in Merge Handling

Published: 2026-11-11 · Severity: routine · Sectors: Technology
Canonical: https://vorant.io/reports/bf71c15a-1280-5bce-99dc-d6f37dc11e39/gitlab-patches-heap-overflow-in-merge-handling
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> GitLab fixed a heap buffer overflow triggered by malicious repositories with oversized conflict markers, causing crashes or heap corruption during merges.

Source: advisories.ncsc.nl — https://advisories.ncsc.nl/2026/ncsc-2026-0480.html

## What to check

- Applies to: The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation: No exploitation in the wild and no public exploit is recorded for the CVEs named.

NCSC-NL published an advisory covering CVE-2026-105437, a heap-based buffer overflow in GitLab Community Edition (CE) and Enterprise Edition (EE). The flaw stems from improper handling of oversized conflict-marker sizes in malicious repositories, which can cause heap corruption or application crashes during merge operations.

GitLab has released fixed versions 19.3.8, 19.4.6, and 19.5.4 to address the issue. The CVSS v3 score is 7.5, indicating a significant denial-of-service/memory-corruption risk, though the advisory does not indicate active exploitation in the wild. Defenders running self-managed GitLab instances should prioritize patching to the fixed versions and review repository ingestion from untrusted sources as a precaution.

## Mentioned in this report

- Vulnerabilities: CVE-2026-105437

Source reporting: https://advisories.ncsc.nl/2026/ncsc-2026-0480.html

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