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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2026-6347

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields in the Mattermost Calls plugin which allows an attacker with access to a support packet to obtain TURN server credentials via the…

HIGH 7.6EPSS 0.27%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.27%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields in the Mattermost Calls plugin which allows an attacker with access to a support packet to obtain TURN server credentials via the plaintext values present in the exported plugin configuration.. Mattermost Advisory ID: MMSA-2026-00605

CVSS 3.1
7.6 HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:L
EPSS
0.27% probability · 18th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-200
Affected
mattermost/mattermost server
Source
responsibledisclosure@mattermost.com
EPSS trend
0%3%5%26 October 2026: 0.27%26 October 202626 October 2026

EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.