virtualenv bash and fish activation scripts execute commands embedded in paths
The generated activate (bash/zsh) and activate.fish scripts interpolate a
shlex.quote-ed value into a position that quotes it a second time. The extra
quotes terminate the quoted run early and leave part of the value parsed as
shell code, so a path containing shell metacharacters runs commands when a user
sources the activation script.
activate is affected through the virtual environment's own path, on the branch
that reports a relocated environment (Virtual environment directory __VIRTUAL_ENV__ does not exist!). For a destination named x'$(id)'y,
shlex.quote emits 'x'"'"'$(id)'"'"'y'; the inner " closes the enclosing
double quote and $(id) is left unquoted. This branch runs whenever the
recorded path is absent, which is the normal case for a virtual environment
copied or distributed to another machine.
activate.fish is affected through the interpreter's Tcl/Tk library paths
(set -gx TCL_LIBRARY '__TCL_LIBRARY__'). The rendered line becomes
''/tcl/(cmd)/lib'', and fish expands the (cmd) left between the adjacent
quoted runs. The same doubling splits a path containing a space into two list
elements, corrupting TCL_LIBRARY and TK_LIBRARY.
This is the same defect class as GHSA-x78j-v8h9-3j2q, which covered
activate.bat.
Fixed in 21.7.13 by moving the placeholders outside the surrounding quotes, so
each value keeps only the quoting shlex.quote applied.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | virtualenv | < 21.7.13 | 21.7.13 |
References
- https://github.com/pypa/virtualenv/security/advisories/GHSA-p58f-9548-mpm2
- https://nvd.nist.gov/vuln/detail/CVE-2026-102925
- https://github.com/pypa/virtualenv/pull/3252
- https://github.com/pypa/virtualenv/commit/4d5a105ec2a2723b8c7f4571bb68f4f71d01e3f6
- https://github.com/pypa/advisory-database/tree/main/vulns/virtualenv/PYSEC-2026-4013.yaml
- https://github.com/pypa/virtualenv
- https://github.com/pypa/virtualenv/releases/tag/21.7.13
- https://pypi.org/project/virtualenv
- CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-78- Platform
- Python (PyPI)
- Package
virtualenv- Disclosed
- 18.09.2026
- Updated
- 11.10.2026 15:18
Sources and licenses
OSV / GitHub Advisory Database - GHSA-p58f-9548-mpm2 - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-4013 - PyPA Advisory Database; CC BY 4.0
Vulnerability history: virtualenv
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 12.2011 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 4
- Medium 3
Disclosures per year
- 2017: 0
- 2018: 0
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 5
earlier: 1
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virtualenv bash and fish activation scripts execute commands embedded in paths this entry
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