Burn-on-Read Message Vulnerability in Mattermost by Mattermost
CVE-2026-2578

4.3MEDIUM

Key Information:

Vendor

Mattermost
Status
Mattermost
Vendor
CVE Published:
16 March 2026

What is CVE-2026-2578?

In Mattermost versions 11.3.x up to 11.3.0, a flaw exists that permits channel members to access unrevealed content of burn-on-read messages even after these messages are deleted. This occurs because the application fails to maintain the intended redacted state of these messages during the deletion process, allowing unauthorized access through WebSocket post deletion events. This opens up risks concerning the confidentiality of sensitive information shared through burn-on-read messaging features.

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Affected Version(s)

Mattermost 11.3.0

Mattermost 11.4.0

Mattermost 11.3.1

References

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

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Joshua Rogers
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