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CVE-2026-4635GO-2026-5820GHSA-PG7C-462J-GRXV

Persistent notification timing attack causing server denial of service

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 10.11.15+incompatible, 11.4.5+incompatible, 11.5.4+incompatible, 11.6.1+incompatible, 11.6.1, and 3 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637

Timeline

  1. CVE published
  2. CISA SSVC assessment

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

  3. Record last updated

Affected versions

  • Mattermost Mattermost

    From 11.6.0 · through 11.6.0; From 11.5.0 · through 11.5.3; From 11.4.0 · through 11.4.4; From 10.11.0 · through 10.11.14

  • github.com/mattermost/mattermost-serverGo

    From 10.11.0+incompatible · fixed in 10.11.15+incompatible; From 11.4.0+incompatible · fixed in 11.4.5+incompatible; From 11.5.0+incompatible · fixed in 11.5.4+incompatible; From 11.6.0+incompatible · fixed in 11.6.1+incompatible

  • github.com/mattermost/mattermost-serverGo

    From 11.6.0 · fixed in 11.6.1

  • github.com/mattermost/mattermost-serverGo

    From 11.5.0 · fixed in 11.5.4

  • github.com/mattermost/mattermost-serverGo

    From 11.4.0 · fixed in 11.4.5

  • github.com/mattermost/mattermost-serverGo

    From 10.11.0 · fixed in 10.11.15

References 1

mattermost.com