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CVE-2026-21865

Discourse topic conversion permission vulnerability for moderators

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, moderators can convert some personal messages to public topics when they shouldn't have access. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. As a workaround, site admin can temporarily revoke the moderation role from untrusted moderators or remove the moderator group from the "personal message enabled groups" site setting until the Discourse instance has been upgraded to a version that has been patched.

Timeline

  1. CVE published
  2. CISA SSVC assessment

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

  3. Record last updated

Affected versions

  • discourse discourse

    fixed in 3.5.4; From 2025.11.0-latest · fixed in 2025.11.2; From 2025.12.0-latest · fixed in 2025.12.1; From 2026.1.0-latest · fixed in 2026.1.0

References 1

GitHub · discourse/discourse