Moderation Flaw in Discourse Discussion Platform by Discourse
CVE-2026-21865

6.5MEDIUM

Key Information:

Vendor

Discourse
Status
Discourse
Vendor
CVE Published:
28 January 2026

What is CVE-2026-21865?

Discourse, an open source discussion platform, has a vulnerability that affects certain versions, allowing moderators to improperly convert private messages into public discussions. This flaw may expose sensitive communications to unauthorized users. It is crucial for site administrators to immediately upgrade to the patched versions or temporarily restrict the moderator role for untrusted users to maintain user privacy and forum integrity.

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Deploy the Patch

Affected Version(s)

discourse < 3.5.4 < 3.5.4

discourse >= 2025.11.0-latest, < 2025.11.2 < 2025.11.0-latest, 2025.11.2

discourse >= 2025.12.0-latest, < 2025.12.1 < 2025.12.0-latest, 2025.12.1

References

https://github.com/discourse/discourse/security/advisorie...
x_refsource_CONFIRM

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
High
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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