CVE-2026-4635CWE-362

Persistent notification timing attack causing server denial of service

Medium · published May 22, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
20.0
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00286 · 20.0th percentile
Weakness
CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Published
2026-05-22T10:28Z
EPSS history
Timeline
  • 22 MAY 10:28Z
    Persistent notification timing attack causing server denial of service
    cvelistv5