CVE-2026-6673

Summary

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

Affected Software

VendorProductVersion RangeStatus
MattermostMattermost11.7.0 <= 11.7.0affected
MattermostMattermost11.6.0 <= 11.6.2affected
MattermostMattermost11.5.0 <= 11.5.5affected
MattermostMattermost10.11.0 <= 10.11.17affected
MattermostMattermost11.8.0unaffected
MattermostMattermost11.7.1unaffected
MattermostMattermost11.6.3unaffected
MattermostMattermost11.5.6unaffected
MattermostMattermost10.11.18unaffected

Weaknesses

  • CWE-306: CWE-306: Missing Authentication for Critical Function

ADP Enrichment

CISA ADP Vulnrichment

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

References