CVE-2026-31869
- Source
- https://cve.org/CVERecord?id=CVE-2026-31869
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31869.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-31869
- Aliases
-
- BIT-discourse-2026-31869
- GHSA-5f9h-vp7v-7vq5
- Published
- 2026-03-20T03:10:43Z
- Modified
- 2026-08-12T03:51:29Z
- Severity
-
- 5.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- Discourse: Composer mentions endpoint leaks hidden group membership through PM `allowed_names` check
- Details
-
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the ComposerController#mentions endpoint reveals hidden group membership to any authenticated user who can message the group. By supplying allowed_names referencing a hidden-membership group and probing arbitrary usernames, an attacker can infer membership based on whether user_reasons returns "private" for a given user. This bypasses group member-visibility controls. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. To work around this issue, restrict the messageable policy of any hidden-membership group to staff or group members only, so untrusted users cannot reach the vulnerable code path.
- Database specific
{ "cna_assigner": "GitHub_M", "cwe_ids": [ "CWE-200", "CWE-285", "CWE-639" ], "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31869.json" }- References
Affected packages
Git / github.com/discourse/discourse
Affected ranges
- Type
- GIT
- Repo
- https://github.com/discourse/discourse
- Events
-
IntroducedFixedIntroducedFixedIntroducedLast Affected
- Database specific
-
Show details
{ "cpe": [ "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*", "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*" ], "extracted_events": [ { "introduced": "2026.1.0" }, { "fixed": "2026.1.2" }, { "introduced": "2026.2.0" }, { "fixed": "2026.2.1" }, { "introduced": "2026.3.0" }, { "last_affected": "2026.3.0" } ], "source": [ "CPE_RANGE", "CPE_STRING" ] }