CVE-2026-26207 (GCVE-0-2026-26207)

Vulnerability from cvelistv5 – Published: 2026-02-26 15:04 – Updated: 2026-02-26 21:33
VLAI
Title
DIscourse's discourse-policy plugin lacks post access check
Summary
Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, `discourse-policy` plugin allows any authenticated user to interact with policies on posts they do not have permission to view. The `PolicyController` loads posts by ID without verifying the current user's access, enabling policy group members to accept/unaccept policies on posts in private categories or PMs they cannot see and any authenticated user to enumerate which post IDs have policies attached via differentiated error responses (information disclosure). The issue is patched in versions 2025.12.2, 2026.1.1, and 2026.2.0 by adding a `guardian.can_see?(@post)` check in the `set_post` before_action, ensuring post visibility is verified before any policy action is processed. As a workaround, disabling the discourse-policy plugin (`policy_enabled = false`) eliminates the vulnerability. There is no other workaround without upgrading.
Severity
5.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-02-26 21:07 UTC
CWE
Assigner
GitHub_M CNA
References
Impacted products
Vendor Product Version
discourse discourse Affected: < 2025.12.2
Affected: >= 2026.1.0-latest, < 2026.1.1
Affected: >= 2026.2.0-latest, < 2026.2.0
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