CVE-2026-4635

MEDIUM

Persistent notification timing attack causing server denial of service

Title source: cna
STIX 2.1

Description

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637

References (1)

Core 1
Core References
Vendor Advisory vendor-advisory
MMSA-2026-00637
https://mattermost.com/security-updates

Scores

CVSS v3 6.5
EPSS 0.0004
EPSS Percentile 10.8%
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-362
Status published
Products (9)
Mattermost/Mattermost 10.11.0 - 10.11.14
Mattermost/Mattermost 10.11.15
Mattermost/Mattermost 11.4.0 - 11.4.4
Mattermost/Mattermost 11.4.5
Mattermost/Mattermost 11.5.0 - 11.5.3
Mattermost/Mattermost 11.5.4
Mattermost/Mattermost 11.6.0
Mattermost/Mattermost 11.6.1
Mattermost/Mattermost 11.7.0
Published May 22, 2026
Tracked Since May 22, 2026