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CVE-2026-16453

Mattermost SAML RelayState forgery allows unauthorized team membership PUBLISHED

Description (CNA)

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to verify the integrity of the SAML RelayState POST parameter which allows an authenticated SAML user to join any team, including invite-only teams, via forging the team_id or invite_id fields in the RelayState.. Mattermost Advisory ID: MMSA-2026-00727

Affected (CNA)

Vendor / productVersions
Mattermost / Mattermostaffected 11.10.0 through 11.10.0; affected 11.7.0 through 11.7.9; affected 11.9.0 through 11.9.1; affected 11.8.0 through 11.8.5; unaffected 11.11.0; unaffected 11.10.1; unaffected 11.7.10; unaffected 11.9.2; unaffected 11.8.6

CWE

CWE-472

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.