gitoxide: CommandForbiddenInModulesConfiguration Bypass in gix_submodule::File::update() Enables Arbitrary Command Execution via .gitmodules

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:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-40034: 0.65% estimated exploitation activity in the next 30 days; percentile 51.27 (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 gixsubmodule::File::update() is the API that gates whether an attacker-supplied .gitmodules file may set update = !<shell command. The function is designed to return Err(CommandForbiddenInModulesConfiguration) unless the !command value came from a trusted local source (.git/config). Git CVE CVE-2019-19604 illustrates why this check is necessary. However, the guard is implemented incorrectly: it checks whether any section with the same submodule name exists from a non-.gitmodules source; it does not verify that the update value came from that section. Once a submodule has been initialized (any workflow that writes submodule.<name.url to .git/config), and the attacker subsequently adds update = !cmd to .gitmodules, the guard passes while the command value falls through to the attacker-controlled file. On an identical repository state, git submodule update aborts with fatal: invalid value for 'submodule.sub.update', while gix::Submodule::update() returns…

Published by the source

5 May 2026, 19:23 UTC

Last modified by the source

30 Jun 2026, 17:41 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f26g-jm89-4g65

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# Patch Next advisory brief: CVE-2026-40034

Advisory: gitoxide: CommandForbiddenInModulesConfiguration Bypass in gix_submodule::File::update() Enables Arbitrary Command Execution via .gitmodules
IDs: CVE-2026-40034, GHSA-f26g-jm89-4g65
Record: https://patchnext.com/advisories/cve-2026-40034 (revision 1, source checked 26 Oct 2026, 15:42 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: gix 0.83.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io gix: affected >= 0.31.0, < 0.83.0; fixed in 0.83.0

## Suggested inspection (read-only)
- crates.io gix: check the installed version with your package manager.

## 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 gix.
- 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://github.com/advisories/GHSA-f26g-jm89-4g65 (GitHub-reviewed advisory GHSA-f26g-jm89-4g65 lists affected ranges: crates.io gix >=0.31.0 <0.83.0)

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