Symlink Attack Affecting virtualenv package, versions [21.14.8,21.14.9)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-VIRTUALENV-21282489
- published21 Oct 2026
- disclosed20 Oct 2026
- creditAnthropic's OSS Scanner
Introduced: 20 Oct 2026
NewCVE-2026-113721 (opens in a new tab)How to fix?
Upgrade virtualenv to version 21.14.9 or higher.
Overview
Affected versions of this package are vulnerable to Symlink Attack via ViaTemplateActivator._generate() and PyEnvCfg.write(), which write generated activation scripts and pyvenv.cfg without first atomically replacing any existing symbolic or hard link at the destination path. ViaTemplateActivator._generate() only removes an existing output file when Path.exists() returns true, meaning a dangling symlink survives the check and redirects the generated activation content to an attacker-controlled location. Similarly, PyEnvCfg.write() opens pyvenv.cfg for writing without first unlinking an existing symbolic or hard link, allowing an attacker who can plant a symlink in the virtualenv output directory to redirect writes and corrupt or overwrite arbitrary files reachable by the creating user.