How severe is CVE-2021-27213?

CVE-2021-27213 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27213 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27213?

CVE-2021-27213 affects Pystemon Project Pystemon. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27213?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-27213 published?

CVE-2021-27213 was published on 2021-02-14 and last updated on 2026-06-17.

CVE-2021-27213

CVE-2021-27213 is a critical-severity vulnerability in Pystemon Project Pystemon with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Pystemon Project Pystemon
Published: 2021-02-14
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is 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.
How severe is CVE-2021-27213?: CVE-2021-27213 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-27213 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27213?: CVE-2021-27213 affects Pystemon Project Pystemon. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27213?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-27213 published?: CVE-2021-27213 was published on 2021-02-14 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:pystemon_project:pystemon:*:*:*:*:*:*:*:*

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