RCE in Pypa Virtualenv

CVE-2026-102925

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.13, the generated activate (bash and zsh) and activate.fish scripts place values already escaped by shlex.quote inside an additional quoted context. In the bash and zsh script, a crafted virtual environment path reaches __VIRTUAL_ENV__ when a relocated environment's recorded directory is absent; in the fish script, crafted Tcl or Tk library paths reach __TCL_LIBRARY__ or __TK_LIBRARY__. The surplus quotes can terminate the data-only quoted run and leave shell metacharacters parsed as commands when a user sources the activation script, allowing code execution with that user's privileges. This issue is fixed in version 21.7.13.

Vulnerability class: Command Injection (OS Command Injection)

Published .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-102925?
CVE-2026-102925 is a high-severity vulnerability in Pypa Virtualenv, classified under OS Command Injection. CVSS score: 7.8/10. Published 2026-09-29.
How severe is CVE-2026-102925?
High severity. CVSS v3 base score is 7.8 out of 10.