Auth bypass in Mattermost
CVE-2026-2461
Mattermost Plugins versions <=11.3 11.0.3 11.2.2 10.10.11.0 fail to implement authorisation checks on comment block modifications, which allows an authorised attacker with editor permission to modify comments created by other board members. Mattermost Advisory ID: MMSA-2025-00559
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (4.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Mattermost — versions 0, 11.4.0, 11.3.1
- Mattermost Server
Weakness classification (CWE)
Public proof-of-concept exploits
References
- mattermost.com/security-updates (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-2461?
- CVE-2026-2461 is a medium-severity vulnerability in Mattermost, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-03-16.
- How severe is CVE-2026-2461?
- Medium severity. CVSS v3 base score is 4.3 out of 10.
- Is CVE-2026-2461 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.