ZeroHour
DashboardNewsCVEsExploitsIncidentsAIBriefAnalyticsEntitiesWatchlistIOCsAsk the feedSourcesFeeds & APIKiosk mode

CVE-2026-6339

—
CVSS 3.1
4.3 medium
EPSS
<1%p2
Published
()
Modified
Description

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

Vendors
mattermost
Products
mattermost server
Weakness
CWE-346
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD CVE.org GitHub PoCs EPSS (0.1%)

In the news

No ingested article mentions this CVE yet.