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
Weakness
The product does not properly verify that the source of data or communication is valid.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Mattermost_server | Mattermost | 11.4.0 (including) | 11.4.4 (excluding) |
| Mattermost_server | Mattermost | 11.5.0 (including) | 11.5.2 (excluding) |
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/111.html
- https://cwe.mitre.org/data/definitions/141.html
- https://cwe.mitre.org/data/definitions/142.html
- https://cwe.mitre.org/data/definitions/160.html
- https://cwe.mitre.org/data/definitions/21.html
- https://cwe.mitre.org/data/definitions/384.html
- https://cwe.mitre.org/data/definitions/385.html
- https://cwe.mitre.org/data/definitions/386.html
- https://cwe.mitre.org/data/definitions/387.html
- https://cwe.mitre.org/data/definitions/388.html
- https://cwe.mitre.org/data/definitions/510.html
- https://cwe.mitre.org/data/definitions/59.html
- https://cwe.mitre.org/data/definitions/60.html
- https://cwe.mitre.org/data/definitions/75.html
- https://cwe.mitre.org/data/definitions/76.html
- https://cwe.mitre.org/data/definitions/89.html