Read the docs
TI-2026-34844 Aliases CVE-2026-47264

Discourse: Don't leak restricted tag group names via tag info

Priority LOW 29CWE-200Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-200.

Summary

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, DetailedTagSerializer#tag_group_names returned every tag group a tag belonged to without filtering against the requesting user's visibility. With SiteSetting.tags_listed_by_group enabled, anonymous and unprivileged users hitting TagsController#info (which is exempt from requires_login) could read the names of tag groups restricted to specific user groups or non-visible categories. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00216 12th percentileScored 2026-11-07
Fix Fixed discourse (discourse): 2026.1.4, 2026.3.1, 2026.4.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
discoursediscourse2026.1.0-latest to before 2026.1.4; 2026.3.0-latest to before 2026.3.1; 2026.4.0-latest to before 2026.4.12026.1.4, 2026.3.1, 2026.4.1Patch availableCNA
  • discourse Vendordiscourse Affected 2026.1.0-latest to before 2026.1.4; 2026.3.0-latest to before 2026.3.1; 2026.4.0-latest to before 2026.4.1 Fixed in 2026.1.4, 2026.3.1, 2026.4.1 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*before 2026.1.0; 2026.1.0 to before 2026.1.4; 2026.3.0 to before 2026.3.1; 2026.4.0 to before 2026.4.1Vulnerablediscourse
cpe:2.3:a:discourse:discourse:2026.5.0:*:*:*:latest:*:*:*2026.5.0Vulnerablediscourse
  • cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:* Versions before 2026.1.0; 2026.1.0 to before 2026.1.4; 2026.3.0 to before 2026.3.1; 2026.4.0 to before 2026.4.1 Vulnerable ·discourse
  • cpe:2.3:a:discourse:discourse:2026.5.0:*:*:*:latest:*:*:* Versions 2026.5.0 Vulnerable ·discourse

Remediation

  • Fix · CNA discourse (discourse) Fixed in 2026.1.4, 2026.3.1, 2026.4.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-47264

References

Advisory 1

  • TI-2021-19656 Denial of Service in discourse CVSS 3.1MEDIUM 6.8
  • TI-2024-36150 Potential Backup file leaked via Nginx in Discourse CVSS 3.1HIGH 7.5
  • TI-2021-18002 RCE via malicious SNS subscription payload CVSS 3.1CRITICAL 10.0
  • TI-2026-24651 Discourse: Open redirect via `sso_destination_url` cookie in `enter` CVSS 4.0MEDIUM 5.1
  • TI-2026-22278 Discourse leaks private topic title and post excerpt via user action API endpoint CVSS 4.0HIGH 8.7
  • TI-2023-24152 Unauthenticated access to new private chat messages in Discourse CVSS 3.1HIGH 7.5
See all 262 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences