CVE-2026-19621CWE-200information-disclosure

CVE-2026-19621

Medium · published October 16, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
15.3
In the wild
Unconfirmed
What it is

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to strip action integration secrets from post payloads before broadcasting post-deletion web socket events and returning thread API responses, which allows an authenticated channel member to obtain server-side webhook URLs and authentication context from interactive-message posts via the post_deleted websocket event or the threads REST API.. Mattermost Advisory ID: MMSA-2026-00766

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:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00249 · 15.3th percentile
Weakness
CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor
Published
2026-10-16T12:17Z
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 OCT 03:28Z
    EPSS moved — → 0%
    epss
  • 16 OCT 07:06Z
    Mattermost leaks interactive-message integration secrets to non-admin users via post-deletion events and thread reads
    cvelistv5
  • 16 OCT 07:06Z
    Mattermost leaks interactive-message integration secrets to non-admin users via post-deletion events and thread reads
    cvelistv5