ByteOS Network

CVE Vulnerability Details :

CVE-2026-6339

PUBLISHED

More Info Official Page

Assigner-Mattermost

Assigner Org ID-9302f53e-dde5-4bf3-b2f2-a83f91ac0eee

Published At-18 May, 2026 | 08:05

Updated At-18 May, 2026 | 12:42

▼CVE Numbering Authority (CNA)

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

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 Products

Vendor

Mattermost, Inc.

Product

Mattermost

Default Status

unaffected

Versions

Affected

From 11.5.0 through 11.5.1 (semver)
From 11.4.0 through 11.4.3 (semver)

Unaffected

11.6.0
11.5.2
11.4.4

Problem Types

Type	CWE ID	Description
CWE	CWE-346	CWE-346: Origin Validation Error

Type: CWE

CWE ID: CWE-346

Description: CWE-346: Origin Validation Error

Metrics

Version	Base score	Base severity	Vector
3.1	4.3	MEDIUM	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Version: 3.1

Base score: 4.3

Base severity: MEDIUM

Vector:

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

Solutions

Update Mattermost to versions 11.6.0, 11.5.2, 11.4.4 or higher.

Credits

finder

game0v3r

References

Hyperlink	Resource
https://mattermost.com/security-updates	vendor-advisory

Hyperlink: https://mattermost.com/security-updates

Resource:

vendor-advisory

▼Authorized Data Publishers (ADP)

CISA ADP Vulnrichment

Affected Products

Affected

Unaffected

Problem Types

Metrics

Metrics Other Info

Impacts

Solutions

Configurations

Workarounds

Exploits

Credits

Timeline

Replaced By

Rejected Reason

References

Affected Products

Metrics

Metrics Other Info

Impacts

Solutions

Configurations

Workarounds

Exploits

Credits

Timeline

Replaced By

Rejected Reason

References