CVE-2025-12421

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.34% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 26.7% of scored records. A rank, not a probability.

NVD base score

9.9 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2025-11-27 17:47Z9 MO AGO

Last updated

2026-02-26 16:07Z6 MO AGO

Reserved

2025-10-28

Assigning CNA

Mattermost

Record state

PUBLISHED

Severity

Critical (CVSS 9.9)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Weaknesses

• CWE-303Incorrect Implementation of Authentication AlgorithmBase

Data version

5.2

Document digest

5453306593c9b4460038bfde2a76b71ee7b53ae566e87b1b93ef04b0f4412983

• mattermost.comhttps://mattermost.com/security-updates