CVE-2026-18223

MediumCVSS 5.0/10Last modified Oct 29, 2026

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 validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747

Metrics

CVSS 3.1 5.0/10CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N

Weakness enumeration

CWE-863

Affected software

Vendor	Product	Versions
Mattermost	Mattermost	>= 11.10.0, <= 11.10.0; >= 11.7.0, <= 11.7.9; >= 11.9.0, <= 11.9.1; >= 11.8.0, <= 11.8.5

References

https://mattermost.com/security-updatesVendor Advisory

Timeline

Published: Oct 16, 2026
Last modified: Oct 29, 2026
NVD status: Analyzed

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