virtualenv: Builtin creation follows linked environment directories

Exploitation

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

CVSS

4.5 · CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

EPSS

• CVE-2026-113716: 0.14% estimated exploitation activity in the next 30 days; percentile 3.69 (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 The builtin creator accepts existing directory symlinks through ensure_dir() and writes environment files through those directories. This permits writes outside the requested destination. Anthropic's OSS Scanner reported this as `ANT-2026-MUFJEG11` in `virtualenv-20261015-005`, received on 15 October 2026.

Affected area Directory preparation before environment files are created.

Attacker-controlled input Another account must be able to prepare linked entries below the chosen destination before creation. The invoking user must have access to the linked destination. This does not require write access to the target itself under the other account.

Affected code The relevant 21.14.8 source is in builtin creator,…

Published by the source

21 Oct 2026, 21:35 UTC

Last modified by the source

29 Oct 2026, 10:55 UTC

Source last checked

30 Oct 2026, 07:20 UTC

1. Revision 5 · amended · 30 Oct 2026

   Amended from osv record BIT-virtualenv-2026-113716

2. Revision 4 · amended · 30 Oct 2026

   Amended from osv record GHSA-cw65-gx24-rc82

3. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cw65-gx24-rc82

4. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-cw65-gx24-rc82

5. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-cw65-gx24-rc82

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# Patch Next advisory brief: CVE-2026-113716

Advisory: virtualenv: Builtin creation follows linked environment directories
IDs: CVE-2026-113716, GHSA-cw65-gx24-rc82
Record: https://patchnext.com/advisories/cve-2026-113716 (revision 5, source checked 30 Oct 2026, 07:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: virtualenv 21.14.9; virtualenv 21.14.9. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI virtualenv: affected < 21.14.9; fixed in 21.14.9
- Bitnami virtualenv: affected < 21.14.9; fixed in 21.14.9

## Suggested inspection (read-only)
- `python -m pip show virtualenv`: prints the installed version. Run with the environment that serves production active.
- Bitnami virtualenv: 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 virtualenv.
- 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-cw65-gx24-rc82 (GitHub-reviewed advisory GHSA-cw65-gx24-rc82 lists affected ranges: PyPI virtualenv >=0 <21.14.9)
- Verified: https://osv.dev/vulnerability/GHSA-cw65-gx24-rc82 (OSV record GHSA-cw65-gx24-rc82 lists affected ranges: PyPI virtualenv >=0 <21.14.9 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-virtualenv-2026-113716 (OSV record BIT-virtualenv-2026-113716 lists affected ranges: Bitnami virtualenv >=0 <21.14.9 (fixed))

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