CVE-2025-55073

low-risk

Published 2025-11-14

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect URL.

Do I need to act?

0.04% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 5.4/10 Medium

NETWORK / LOW complexity

Affected Products (1)

Mattermost Server

Affected Vendors

Mattermost

References (1)

Vendor Advisory https://mattermost.com/security-updates

/ 100

low-risk

Severity 21/34 · High

Exploitability 0/34 · Minimal

Exposure 5/34 · Minimal