What is CVE-2021-27213?

CVE-2021-27213 is a critical-severity vulnerability in Pystemon Project, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2021-02-14.

How severe is CVE-2021-27213?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Deserialization in Pystemon Project

CVE-2021-27213

config.py in pystemon before 2021-02-13 allows code execution via YAML deserialization because SafeLoader and safe_load are not used.

Vulnerability class: Insecure Deserialization

Published 2021-02-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.026 (85.0th percentile), scored 2026-10-08.

Low probability of exploitation in the next 30 days, but still tracked. 85th percentile — 85.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.026 · newest: 0.026 · change: 0.000

Affected products

Pystemon Project

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

github.com/cvandeplas/pystemon/commit/dbeb87afefdb63de2f4cff69b6f10c5965d14b54 (Patch, Third Party Advisory)
www.huntr.dev/bounties/1-other-pystemon/ (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-27213?: CVE-2021-27213 is a critical-severity vulnerability in Pystemon Project, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2021-02-14.
How severe is CVE-2021-27213?: Critical severity. CVSS v3 base score is 9.8 out of 10.