virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection (CVE-2026-102938) | HOL Guard CVE

Medium · CVSS 5.8CVE-2026-102938

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

Answer in brief

CVE-2026-102938 records a Medium severity (CVSS 5.8) vulnerability in virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection. The current sources do not mark it as known exploited. The current feed maps pypa/virtualenv (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 29, 2026Updated Sep 29, 2026Source checked Sep 29, 2026First seen by HOL Sep 29, 2026Material review Sep 29, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.8
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps pypa/virtualenv (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
pypa/virtualenvgeneric	<21.7.11	21.7.11

Recommended response

Check inventory. Check lockfiles and deployed manifests for pypa/virtualenv.
Review the reported fix. Update pypa/virtualenv to 21.7.11 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 29, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.