CVE-2026-6339 — Missing request origin validation on burn-on-read reveal endpoint

CVE-2026-6339

Missing request origin validation on burn-on-read reveal endpoint PUBLISHED

Description (CNA)

Mattermost versions 11.5.x <= 11.5.1, 11.4.x <= 11.4.3 fail to validate the X-Requested-With header on the burn-on-read reveal endpoint which allows an authenticated channel member to force the reveal of a burn-on-read message without recipient consent via a crafted Markdown image tag.. Mattermost Advisory ID: MMSA-2026-00636

Affected (CNA)

Vendor / product	Versions
Mattermost / Mattermost	affected 11.5.0 through 11.5.1; affected 11.4.0 through 11.4.3; unaffected 11.6.0; unaffected 11.5.2; unaffected 11.4.4

CWE

CWE-346

References

https://mattermost.com/security-updates

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.