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CVE-2026-2578GO-2026-4734GHSA-3RHR-JR63-HWQ5

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 10.11.11+incompatible, 11.2.3+incompatible, 11.3.1+incompatible, 8.0.0-20260127062706-c6b205f0d770, 5.3.2-0.20260127062706-c6b205f0d770, and 3 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • Mattermost Mattermost

    From 11.3.0 · through 11.3.0

  • github.com/mattermost/mattermost-serverGo

    From 10.11.0-rc1+incompatible · fixed in 10.11.11+incompatible; From 11.2.0-rc1+incompatible · fixed in 11.2.3+incompatible; From 11.3.0-rc1+incompatible · fixed in 11.3.1+incompatible

  • github.com/mattermost/mattermost-server/v5Go

    All versions

  • github.com/mattermost/mattermost-server/v6Go

    All versions

  • github.com/mattermost/mattermost/server/v8Go

    fixed in 8.0.0-20260127062706-c6b205f0d770

  • github.com/mattermost/mattermost-serverGo

    fixed in 5.3.2-0.20260127062706-c6b205f0d770

  • github.com/mattermost/mattermost-serverGo

    From 10.11.0-rc1 · fixed in 10.11.11

  • github.com/mattermost/mattermost-serverGo

    From 11.2.0-rc1 · fixed in 11.2.3

  • github.com/mattermost/mattermost-serverGo

    From 11.3.0-rc1 · fixed in 11.3.1

References 1

mattermost.com