CVE-2026-9708

Summary

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683

Affected Software

VendorProductVersion RangeStatus
MattermostMattermost11.7.0 <= 11.7.2affected
MattermostMattermost11.6.0 <= 11.6.4affected
MattermostMattermost10.11.0 <= 10.11.19affected
MattermostMattermost11.8.0unaffected
MattermostMattermost11.7.3unaffected
MattermostMattermost11.6.5unaffected
MattermostMattermost10.11.20unaffected

Weaknesses

  • CWE-639: CWE-639: Authorization Bypass Through User-Controlled Key

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References