CVE-2026-2578

Information Disclosure via WebSocket Event When Deleting Unrevealed Burn on Read Posts

CVSS 4.3 MEDIUMEPSS 0.2%CWE-201

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 4.3EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch referenciado

Lifecycle

16 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Mattermost versions 11.3.x <= 11.3.0 fail to preserve the redacted state of burn-on-read posts during deletion which allows channel members to access unrevealed burn-on-read message contents via the WebSocket post deletion event.. Mattermost Advisory ID: MMSA-2026-00579

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

Affected products

Mattermost · Mattermost

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References

https://mattermost.com/security-updates