virtualenv: Bash activator leaves the --prompt value unescaped in PS1 when promptvars is off, so prompt expansion later executes it (regression in 21.14.9)

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-115586: 0.27% estimated exploitation activity in the next 30 days; percentile 19.39 (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 bash activator puts the caller-supplied prompt value into `PS1` unescaped whenever `promptvars` is off at activation time, and assumes prompt expansion can never run afterwards. `promptvars` and posix mode are runtime shell state, not a property of the activation moment: re-enabling prompt expansion in the same shell (`shopt -s promptvars`, `set -o posix`) or starting an interactive child bash that inherits the exported `PS1` makes bash expand the stored value and run the command substitution in it. An attacker who controls the prompt value gets command execution as the user who sources `bin/activate`. This is a regression. 21.14.8 escaped `$` and the backtick unconditionally and stays inert under the same sequence. The 21.14.9 fix for GHSA-6w3r-xr62-4xcp (#3418) rewrote that block and left bash with a path that stores the raw value whenever `promptvars` is off.

Affected area Activation scripts (activate, activate.bat, activate.csh, activate.fish, activate.nu,…

Published by the source

23 Oct 2026, 20:47 UTC

Last modified by the source

29 Oct 2026, 10:55 UTC

Source last checked

30 Oct 2026, 07:20 UTC

1. Revision 7 · amended · 30 Oct 2026

   Amended from osv record BIT-virtualenv-2026-115586

2. Revision 6 · amended · 30 Oct 2026

   Amended from osv record GHSA-cx6f-vjhg-g3cc

3. Revision 5 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cx6f-vjhg-g3cc

4. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cx6f-vjhg-g3cc

5. Revision 3 · amended · 24 Oct 2026

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

6. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-cx6f-vjhg-g3cc

7. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-cx6f-vjhg-g3cc

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# Patch Next advisory brief: CVE-2026-115586

Advisory: virtualenv: Bash activator leaves the --prompt value unescaped in PS1 when promptvars is off, so prompt expansion later executes it (regression in 21.14.9)
IDs: CVE-2026-115586, GHSA-cx6f-vjhg-g3cc
Record: https://patchnext.com/advisories/cve-2026-115586 (revision 7, 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 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: virtualenv 21.14.13; virtualenv 21.14.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI virtualenv: affected >= 21.14.9, < 21.14.13; fixed in 21.14.13
- Bitnami virtualenv: affected >= 21.14.9, < 21.14.13; fixed in 21.14.13

## 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-cx6f-vjhg-g3cc (GitHub-reviewed advisory GHSA-cx6f-vjhg-g3cc lists affected ranges: PyPI virtualenv >=21.14.9 <21.14.13)
- Verified: https://osv.dev/vulnerability/GHSA-cx6f-vjhg-g3cc (OSV record GHSA-cx6f-vjhg-g3cc lists affected ranges: PyPI virtualenv >=21.14.9 <21.14.13 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-virtualenv-2026-115586 (OSV record BIT-virtualenv-2026-115586 lists affected ranges: Bitnami virtualenv >=21.14.9 <21.14.13 (fixed))

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