How severe is CVE-2025-43921?

CVE-2025-43921 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2025-43921 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-43921?

CVE-2025-43921 affects Gnu Mailman. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-43921?

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

Does CVE-2025-43921 have an EU (EUVD) identifier?

Yes. CVE-2025-43921 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12590.

When was CVE-2025-43921 published?

CVE-2025-43921 was published on 2025-04-20 and last updated on 2026-06-17.

CVE-2025-43921

CVE-2025-43921 is a medium-severity vulnerability in Gnu Mailman with a CVSS 3.x base score of 5.3. 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-863.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (36th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-12590
Weakness: CWE-863
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), allows unauthenticated attackers to create lists via the /mailman/create endpoint. 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-2025-43921?: GNU Mailman 2.1.39, as bundled in cPanel (and WHM), allows unauthenticated attackers to create lists via the /mailman/create endpoint. NOTE: multiple third parties report that they are unable to reproduce this, regardless of whether cPanel or WHM is used.
How severe is CVE-2025-43921?: CVE-2025-43921 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2025-43921 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-43921?: CVE-2025-43921 affects Gnu Mailman. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-43921?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-43921 have an EU (EUVD) identifier?: Yes. CVE-2025-43921 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12590.
When was CVE-2025-43921 published?: CVE-2025-43921 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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