GitHub Copilot CLI: Nested Bare Repository Can Execute Arbitrary Commands via core.fsmonitor

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.5 · CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-45033: 0.35% estimated exploitation activity in the next 30 days; percentile 28.69 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A security vulnerability has been identified in GitHub Copilot CLI where a malicious bare git repository nested inside a project directory can achieve arbitrary code execution when the agent performs git operations. By exploiting git's automatic bare repository discovery during directory traversal, an attacker can set core.fsmonitor or other executable config keys to run arbitrary commands without user awareness or approval. Details Git supports bare repositories — repositories without a working tree — which can be discovered automatically when git traverses the directory hierarchy looking for a .git directory. When git discovers a bare repository, it reads and applies its configuration, including keys that specify external commands to execute. The vulnerability arises because git's core.fsmonitor config key (and 15+ similar keys such as core.hookspath, diff.external, merge.tool, etc.) can specify arbitrary shell commands that git will execute as part of normal operations…

Published by the source

11 May 2026, 16:16 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:53 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9ccr-r5hg-74gf

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9ccr-r5hg-74gf

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# Patch Next advisory brief: CVE-2026-45033

Advisory: GitHub Copilot CLI: Nested Bare Repository Can Execute Arbitrary Commands via core.fsmonitor
IDs: CVE-2026-45033, GHSA-9ccr-r5hg-74gf
Record: https://patchnext.com/advisories/cve-2026-45033 (revision 3, source checked 26 Oct 2026, 12:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @github/copilot 1.0.43. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @github/copilot: affected <= 1.0.42; fixed in 1.0.43

## Suggested inspection (read-only)
- `npm ls @github/copilot --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @github/copilot.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9ccr-r5hg-74gf (OSV record GHSA-9ccr-r5hg-74gf lists affected ranges: npm @github/copilot >=0 <1.0.43 (fixed))
- Verified: https://github.com/advisories/GHSA-9ccr-r5hg-74gf (GitHub-reviewed advisory GHSA-9ccr-r5hg-74gf lists affected ranges: npm @github/copilot >=0 <=1.0.42)

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