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Mattermost fails to preserve the redacted state of burn-on-read posts during deletion

Moderate severity GitHub Reviewed Published Mar 16, 2026 to the GitHub Advisory Database • Updated Mar 17, 2026

Package

gomod github.com/mattermost/mattermost-server (Go)

Affected versions

< 5.3.2-0.20260127062706-c6b205f0d770
>= 10.11.0-rc1, < 10.11.11
>= 11.2.0-rc1, < 11.2.3
>= 11.3.0-rc1, < 11.3.1

Patched versions

5.3.2-0.20260127062706-c6b205f0d770
10.11.11
11.2.3
11.3.1
gomod github.com/mattermost/mattermost/server/v8 (Go)
< 8.0.0-20260127062706-c6b205f0d770
8.0.0-20260127062706-c6b205f0d770

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

References

Published by the National Vulnerability Database Mar 16, 2026
Published to the GitHub Advisory Database Mar 16, 2026
Last updated Mar 17, 2026
Reviewed Mar 17, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(7th percentile)

Weaknesses

Insertion of Sensitive Information Into Sent Data

The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. Learn more on MITRE.

CVE ID

CVE-2026-2578

GHSA ID

GHSA-3rhr-jr63-hwq5

Source code

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