CVE-2026-102938

virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection

Published Sep 29, 2026 CVSS 4.0 · 5.8 Medium EPSS < 1% KEV · Not listed
Description
virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-9h9j-4vrj-gf7g virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection
History
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
First Time appeared Pypa
Pypa virtualenv
Python
Python virtualenv
Vendors & Products Pypa
Pypa virtualenv
Python
Python virtualenv
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.
Title virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection
Weaknesses CWE-93
References
Metrics cvssV4_0

{'score': 5.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 30, 2026, 7:53 PM
Reserved
Sep 29, 2026, 8:24 PM
Status
Awaiting Analysis
Published
Sep 29, 2026, 9:17 PM
Modified
Sep 30, 2026, 8:17 PM
Severity
Moderate
Public date
Sep 29, 2026, 8:58 PM