PYSEC-2026-4013

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/virtualenv/PYSEC-2026-4013.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-4013
Aliases
Published
2026-09-18T04:37:14Z
Modified
2026-09-30T16:45:02Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H CVSS Calculator
Summary
virtualenv bash and fish activation scripts execute commands embedded in paths
Details

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.

References
Credits
    • Bernát Gábor - FINDER

Affected packages

PyPI / virtualenv

Package

Name
virtualenv
View open source insights on deps.dev
Purl
pkg:pypi/virtualenv

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
21.7.13

Affected versions

0.*
0.8
0.8.1
0.8.2
0.8.3
0.8.4
0.9
0.9.1
0.9.2
1.*
1.0
1.1
1.2
1.3
1.3.1
1.3.2
1.3.3
1.3.4
1.4rc1
1.4
1.4.1
1.4.2
1.4.3
1.4.4
1.4.5
1.4.6
1.4.7
1.4.8
1.4.9
1.5
1.5.1
1.5.2
1.6
1.6.1
1.6.2
1.6.3
1.6.4
1.7
1.7.1
1.7.1.1
1.7.1.2
1.7.2
1.8
1.8.1
1.8.2
1.8.3
1.8.4
1.9
1.9.1
1.10
1.10.1
1.11
1.11.1
1.11.2
1.11.3
1.11.4
1.11.5
1.11.6
12.*
12.0
12.0.1
12.0.2
12.0.4
12.0.5
12.0.6
12.0.7
12.1.0
12.1.1
13.*
13.0.0
13.0.1
13.0.2
13.0.3
13.1.0
13.1.1
13.1.2
14.*
14.0.0
14.0.1
14.0.2
14.0.3
14.0.4
14.0.5
14.0.6
15.*
15.0.0
15.0.1
15.0.2
15.0.3
15.1.0
15.2.0
16.*
16.0.0
16.1.0
16.2.0
16.3.0
16.3.1.dev0
16.4.0
16.4.1
16.4.3
16.4.4.dev0
16.5.0
16.6.0
16.6.1
16.6.2
16.7.0
16.7.1
16.7.2
16.7.3
16.7.4
16.7.5
16.7.6
16.7.7
16.7.8
16.7.9
16.7.10
16.7.11
16.7.12
20.*
20.0.0b1
20.0.0b2
20.0.0
20.0.1
20.0.2
20.0.3
20.0.4
20.0.5
20.0.6
20.0.7
20.0.8
20.0.9
20.0.10
20.0.11
20.0.12
20.0.13
20.0.14
20.0.15
20.0.16
20.0.17
20.0.18
20.0.19
20.0.20
20.0.21
20.0.22
20.0.23
20.0.24
20.0.25
20.0.26
20.0.27
20.0.28
20.0.29
20.0.30
20.0.31
20.0.32
20.0.33
20.0.34
20.0.35
20.1.0
20.2.0
20.2.1
20.2.2
20.3.0
20.3.1
20.4.0
20.4.1
20.4.2
20.4.3
20.4.4
20.4.5
20.4.6
20.4.7
20.5.0
20.6.0
20.7.0
20.7.1
20.7.2
20.8.0
20.8.1
20.9.0
20.10.0
20.11.0
20.11.1
20.11.2
20.12.0
20.12.1
20.13.0
20.13.1
20.13.2
20.13.3
20.13.4
20.14.0
20.14.1
20.15.0
20.15.1
20.16.0
20.16.1
20.16.2
20.16.3
20.16.4
20.16.5
20.16.6
20.16.7
20.17.0
20.17.1
20.18.0
20.19.0
20.20.0
20.21.0
20.21.1
20.22.0
20.23.0
20.23.1
20.24.0
20.24.1
20.24.2
20.24.3
20.24.4
20.24.5
20.24.6
20.24.7
20.25.0
20.25.1
20.25.2
20.25.3
20.26.0
20.26.1
20.26.2
20.26.3
20.26.4
20.26.5
20.26.6
20.27.0
20.27.1
20.28.0
20.28.1
20.29.0
20.29.1
20.29.2
20.29.3
20.30.0
20.31.0
20.31.1
20.31.2
20.32.0
20.33.0
20.33.1
20.34.0
20.35.0
20.35.1
20.35.2
20.35.3
20.35.4
20.36.0
20.36.1
20.38.0
20.39.0
20.39.1
21.*
21.0.0
21.1.0
21.2.0
21.2.1
21.2.2
21.2.3
21.2.4
21.3.0
21.3.1
21.3.2
21.3.3
21.4.0
21.4.1
21.4.2
21.4.3
21.5.0
21.5.1
21.5.2
21.6.0
21.6.1
21.7.0
21.7.1
21.7.2
21.7.3
21.7.4
21.7.5
21.7.6
21.7.7
21.7.8
21.7.9
21.7.10
21.7.11
21.7.12

Database specific

source 
"https://github.com/pypa/advisory-database/blob/main/vulns/virtualenv/PYSEC-2026-4013.yaml"