CVE-2026-16453
HIGH
CVSS 7.1
Published: 2026-10-16
Modified: 2026-10-16
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Description
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
Quick Facts
| CVE ID | CVE-2026-16453 |
| CVSS Score | 7.1 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N |
| Published | 2026-10-16 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |