Poetry: virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration
Affects poetrySource GCVE Database
Not known to be exploited · CVSS 5.8 Medium : upgrade to 2.5.0 or 1.2.2_1 when convenient.
Data as of 30 Oct 2026, 08:30 UTC
- Patch
- Available – fixed in 2.5.0, 1.2.2_1
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 29 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade poetry to 2.5.0 or 1.2.2_1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewpoetrypkg:brew/poetryOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Apply the official patches by upgrading Poetry to version 1.2.2_1 or later, or 2.5.0 or later, where the issue is fixed by sanitizing line boundaries in prompt values. As a workaround, avoid passing externally influenced data as the virtualenv prompt and strip any line boundary characters from values used with --prompt or VIRTUALENV_PROMPT.
Description
A vulnerability in Poetry's virtualenv handling allows crafted prompt values containing line boundaries to inject additional configuration lines into the pyvenv.cfg file. This can overwrite critical configuration keys such as 'home', which tooling uses to locate the base interpreter. The issue arises because pyvenv.cfg is line-based with no escape syntax, and the write operation did not sanitize line boundaries, allowing injection of arbitrary config lines. This can lead to configuration corruption or redirection of interpreter paths when the prompt value is influenced by external input such as CI job templates or environment variables. Fixed in Poetry versions 1.2.2_1 and 2.5.0 by collapsing line boundaries to spaces during serialization.
References
- github.com/pypa/virtualenv/security/advisories/GHSA-9h9j-4vrj-gf7g (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-102938 (opens in a new tab)
- github.com/pypa/virtualenv/pull/3247 (opens in a new tab)
- github.com/pypa/virtualenv/commit/a30f995461043acb6cacbf3a890951563ccf7140 (opens in a new tab)
- github.com/pypa/advisory-database/tree/main/vulns/virtualenv/PYSEC-2026-4012.yaml (opens in a new tab)
- github.com/pypa/virtualenv (opens in a new tab)
- github.com/pypa/virtualenv/releases/tag/21.7.11 (opens in a new tab)
- pypi.org/project/virtualenv (opens in a new tab)