CVE-2026-2578
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Burn-on-Read Data Exposure via Post Deletion in Mattermost

Publication date: 2026-03-16

Last updated on: 2026-03-18

Assigner: Mattermost, Inc.

Description
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

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Meta Information

Published
2026-03-16
Last Modified
2026-03-18
Generated
2026-07-06
AI Q&A
2026-03-16
EPSS Evaluated
2026-07-05
NVD
CVE-2026-2578
EUVD
EUVD-2026-12415

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
mattermost mattermost_server From 11.3.0 (inc) to 11.3.1 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-201 The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

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Executive Summary

This vulnerability affects Mattermost versions 11.3.x up to and including 11.3.0. It occurs because the software fails to maintain the redacted state of burn-on-read posts when they are deleted. As a result, channel members can access the contents of these burn-on-read messages, which were supposed to remain unrevealed, through the WebSocket post deletion event.

Impact Analysis

The impact of this vulnerability is that sensitive information intended to be hidden or ephemeral in burn-on-read posts can be exposed to channel members. This could lead to unauthorized disclosure of confidential or private message contents, potentially compromising privacy and security within the affected Mattermost channels.

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