CVE-2021-27213 json
config.py in pystemon before 2021-02-13 allows code execution via YAML deserialization because SafeLoader and safe_load are not used.
published 5y ago modified 4mo ago also EUVD-2021-13978
- cvss
- 9.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.7%
- EPSS 2.7% chance of exploitation in 30 days, percentile 86%
- public exploits
- 0
- none known
Summary
config.py in pystemon before 2021-02-13 allows code execution via YAML deserialization because SafeLoader and safe_load are not used.
Patch / fix
Is CVE-2021-27213 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerExploit prediction
2.73% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- huntr.dev https://www.huntr.dev/bounties/1-other-pystemon/ referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.5 | AV:N/AC:L/Au:N/C:P/I:P/A:P |
Classification
- Weakness
-
- CWE-502 Deserialization of Untrusted Data
References
-
github.com
/cvandeplas/pystemon/commit/dbeb87afefdb63de2f4cff69b6f10c5965d14b54
patch, third-party-advisory
-
huntr.dev
/bounties/1-other-pystemon/
exploit, third-party-advisory
Sources
- CVE List CVE-2021-27213
- NVD CVE-2021-27213
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.