CVE-2026-33410

Summary

Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have two authorization issues in the chat direct message API. First, when creating a direct message channel or adding users to an existing one, the target_groups parameter was passed directly to the user resolution query without checking group or member visibility for the acting user. An authenticated chat user could craft an API request with a known private/hidden group name and receive a channel containing that group's members, leaking their identities. Second, can_chat? only checked group membership, not the chat_enabled user preference. A chat-disabled user could create or query DM channels between other users via the direct messages API, potentially exposing private last_message content from the serialized channel response. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Affected Software

Weaknesses

• CWE-863: CWE-863: Incorrect Authorization

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://github.com/discourse/discourse/security/advisories/GHSA-2m5j-6v2r-cq2h

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