6.5

CVE-2025-12689: DoS in Calls plugin via malformed UTF-8 in WebSocket request

Analyzed
AliasesGHSA-j5vq-62gr-8v3rGO-2025-4255
Published 17-12-2025Last modified 17-12-2025

Vulnerability summary

CVE-2025-12689 is a medium (CVSS 6.5) vulnerability in mattermost. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 21.3% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 6.5, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.29%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 2
OPENSUSE-SU-2026:21483-1SUSE-SU-2026:0037-1

Timeline

  1. 17-12-2025
    PublishedVulnerability first disclosed.
  2. 17-12-2025
    Last modifiedVulnerability information updated.

Description

Mattermost versions 11.0.x <= 11.0.4, 10.12.x <= 10.12.2, 10.11.x <= 10.11.6 fail to check WebSocket request field for proper UTF-8 format, which allows attacker to crash Calls plug-in via sending malformed request.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.29%

Chance of exploitation in the next 30 days

Percentile

21%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.29% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Mattermost2 products
  • mattermost≥ 11.0.0, ≤ 11.0.4 | ≥ 10.12.0, ≤ 10.12.2 | ≥ 10.11.0, ≤ 10.11.6
  • mattermost_server≥ 10.11.0, < 10.11.7 | ≥ 10.12.0, < 10.12.3 | ≥ 11.0.0, < 11.0.5
Github.com/mattermost1 product
  • mattermost-plugin-calls< 1.11.0

2 vendors · 3 products

References

5 links