What is CVE-2025-43920?

CVE-2025-43920 is a medium-severity vulnerability in Gnu Mailman, classified under OS Command Injection. CVSS score: 5.4/10. Published 2025-04-20.

How severe is CVE-2025-43920?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Is CVE-2025-43920 known to be exploited?

4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

RCE in Gnu Mailman

CVE-2025-43920

GNU Mailman 2.1.39, as bundled in cPanel (and WHM), in certain external archiver configurations, allows unauthenticated attackers to execute arbitrary OS commands via shell metacharacters in an email Subject line. NOTE: multiple third parties report that they are unable to reproduce this, regardless of whether cPanel or WHM is used.

Vulnerability class: Command Injection (OS Command Injection)

EPSS: 0.006 (43.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N.

Affected products

Gnu Mailman — versions 2.1.39

Weakness classification (CWE)

CWE-78 — OS Command Injection

Public proof-of-concept exploits

References

cve@mitre.org (Product)
cve@mitre.org (Exploit, Third Party Advisory)
cve@mitre.org
cve@mitre.org

Frequently asked questions

What is CVE-2025-43920?: CVE-2025-43920 is a medium-severity vulnerability in Gnu Mailman, classified under OS Command Injection. CVSS score: 5.4/10. Published 2025-04-20.
How severe is CVE-2025-43920?: Medium severity. CVSS v3 base score is 5.4 out of 10.
Is CVE-2025-43920 known to be exploited?: 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.