Command injection in Yamale

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-2021-38305: 2.49% estimated exploitation activity in the next 30 days; percentile 84.66 (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.

23andMe Yamale before 3.0.8 allows remote attackers to execute arbitrary code via a crafted schema file. The schema parser uses eval as part of its processing, and tries to protect from malicious expressions by limiting the builtins that are passed to the eval. When processing the schema, each line is run through Python's eval function to make the validator available. A well-constructed string within the schema rules can execute system commands; thus, by exploiting the vulnerability, an attacker can run arbitrary code on the image that invokes Yamale.

Published by the source

11 Aug 2021, 15:19 UTC

Last modified by the source

19 Nov 2024, 18:33 UTC

Source last checked

26 Oct 2026, 13:27 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-435p-f82x-mxwm

2. Revision 2 · amended · 25 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-435p-f82x-mxwm

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# Patch Next advisory brief: CVE-2021-38305

Advisory: Command injection in Yamale
IDs: CVE-2021-38305, GHSA-435p-f82x-mxwm
Record: https://patchnext.com/advisories/cve-2021-38305 (revision 3, source checked 26 Oct 2026, 13:27 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: yamale 3.0.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI yamale: affected < 3.0.8; fixed in 3.0.8

## Suggested inspection (read-only)
- `python -m pip show yamale`: prints the installed version. Run with the environment that serves production active.

## 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 yamale.
- 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-435p-f82x-mxwm (OSV record GHSA-435p-f82x-mxwm lists affected ranges: PyPI yamale >=0 <3.0.8 (fixed))
- Verified: https://github.com/advisories/GHSA-435p-f82x-mxwm (GitHub-reviewed advisory GHSA-435p-f82x-mxwm lists affected ranges: PyPI yamale >=0 <3.0.8)

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