CVSS 4.3 (medium) · published 2026-10-16
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 (NVD): mattermost mattermost_server
Fixed in (NVD): 11.7.11, 11.8.6, 11.9.2
Weakness: CWE-770
Source: NVD CVE-2026-19867
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