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CVE-2026-18799

Mattermost Server fails to restrict Slack import account binding, allowing team admins to forge posts as existing users 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 restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team and forge posts attributed to those users' identities via a crafted Slack export containing target users' email addresses.. Mattermost Advisory ID: MMSA-2026-00757

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-862

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.