How severe is CVE-2025-43920?

CVE-2025-43920 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-43920 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-43920?

CVE-2025-43920 affects Gnu Mailman. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-43920?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-43920 have an EU (EUVD) identifier?

Yes. CVE-2025-43920 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12591.

When was CVE-2025-43920 published?

CVE-2025-43920 was published on 2025-04-20 and last updated on 2026-06-17.

CVE-2025-43920

CVE-2025-43920 is a medium-severity vulnerability in Gnu Mailman with a CVSS 3.x base score of 5.4. 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-78.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-12591
Weakness: CWE-78
Affected product: Gnu Mailman
Published: 2025-04-20
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2025-43920?: CVE-2025-43920 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-43920 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-43920?: CVE-2025-43920 affects Gnu Mailman. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-43920?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-43920 have an EU (EUVD) identifier?: Yes. CVE-2025-43920 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12591.
When was CVE-2025-43920 published?: CVE-2025-43920 was published on 2025-04-20 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:gnu:mailman:*:*:*:*:*:*:*:*

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