CVE-2026-10819

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.6.0 through 11.6.5 Mattermost versions 10.11.0 through 10.11.20 Mattermost versions 11.8.0 through 11.8.1 Mattermost versions 11.7.0 through 11.7.4

Description An authenticated attacker can cause a denial of service by uploading a specially crafted animated GIF as a custom emoji. This occurs because the system fails to limit the number of frames and does not enforce the file size cap during the upload process.

Recommendations Update Mattermost versions 11.6.0 through 11.6.5 to a version newer than 11.6.5. Update Mattermost versions 10.11.0 through 10.11.20 to a version newer than 10.11.20. Update Mattermost versions 11.8.0 through 11.8.1 to a version newer than 11.8.1. Update Mattermost versions 11.7.0 through 11.7.4 to a version newer than 11.7.4.