medium4.3
CVE-2026-19867
Mattermost versions 11.10.x <= 11.10.0, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to cap the number and size of mention keys stored in a user'…
Impact
Mattermost versions 11.10.x <= 11.10.0, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to cap the number and size of mention keys stored in a user's notification properties, and to bound the quadratic multibyte-keyword matching performed for each post, which allows an authenticated user to degrade post-processing latency and consume excessive CPU on behalf of other members of any channel they share via storing an oversized notify_props.mention_keys list on their own profile.. Mattermost Advisory ID: MMSA-2026-00773
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 11.7.0 before 11.7.11 from 11.8.0 before 11.8.6 from 11.9.0 before 11.9.2 Version 11.10.0 |