virtualenv activate runs commands from the environment name in zsh with PROMPT_SUBST

Exploitation

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

CVSS

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

EPSS

• CVE-2026-113726: 0.34% estimated exploitation activity in the next 30 days; percentile 28.08 (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.

Impact zsh users activate an environment with the bash `activate` script, which puts the environment name into `PS1`. Since 21.13.0 the script escapes backslashes, dollar signs and backticks in that name, but only when `BASH_VERSION` is set, so zsh gets the raw value. With the `PROMPT_SUBST` option set, zsh runs parameter expansion, command substitution and arithmetic expansion on `PS1` each time it draws the prompt. A name that contains `$(...)`, backticks or `${...}` then runs as commands in the user's shell, once per prompt. The name comes from the environment directory, or from `--prompt` or `VIRTUALENV_PROMPT`. After you create an environment with: ```console $ virtualenv 'x$(touch PWNED)y' ``` `source 'x$(touch PWNED)y/bin/activate'` in a zsh session with `PROMPT_SUBST` set creates `PWNED`, and the prompt shows `(xy)`. Passing that value as `--prompt` to an environment with a plain name has the same effect. Without `PROMPT_SUBST`, zsh shows the name as text and runs…

Published by the source

21 Oct 2026, 16:46 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-2026-113726

2. Revision 4 · amended · 30 Oct 2026

   Amended from osv record GHSA-5vjq-rrrf-7h2q

3. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5vjq-rrrf-7h2q

4. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-5vjq-rrrf-7h2q

5. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-5vjq-rrrf-7h2q

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# Patch Next advisory brief: CVE-2026-113726

Advisory: virtualenv activate runs commands from the environment name in zsh with PROMPT_SUBST
IDs: CVE-2026-113726, GHSA-5vjq-rrrf-7h2q
Record: https://patchnext.com/advisories/cve-2026-113726 (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: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: virtualenv 21.14.4; virtualenv 21.14.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI virtualenv: affected < 21.14.4; fixed in 21.14.4
- Bitnami virtualenv: affected < 21.14.4; fixed in 21.14.4

## 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-5vjq-rrrf-7h2q (GitHub-reviewed advisory GHSA-5vjq-rrrf-7h2q lists affected ranges: PyPI virtualenv >=0 <=21.14.3)
- Verified: https://osv.dev/vulnerability/GHSA-5vjq-rrrf-7h2q (OSV record GHSA-5vjq-rrrf-7h2q lists affected ranges: PyPI virtualenv >=0 <21.14.4 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-virtualenv-2026-113726 (OSV record BIT-virtualenv-2026-113726 lists affected ranges: Bitnami virtualenv >=0 <21.14.4 (fixed))

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