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TI-2026-19116 Aliases CVE-2026-23743

Discourse allows permalinks to restricted resources to leak resource slugs to unauthorized users

Priority LOW 36CWE-200Published · Updated

Key facts

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

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-200.

Summary

Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, permalinks pointing to access-restricted resources (private topics, categories, posts, or hidden tags) were redirecting users to URLs containing the resource slug, even when the user didn't have access to view the resource. This leaked potentially sensitive information (e.g., private topic titles) via the redirect Location header and the 404 page's search box. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. No known workarounds are available.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00291 21st percentileScored 2026-11-07
Fix Fixed discourse (discourse): 3.5.4, 2025.11.2, 2025.12.1 +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
discoursediscoursebefore 3.5.4; 2025.11.0-latest to before 2025.11.2; 2025.12.0-latest to before 2025.12.1; 2026.1.0-latest to before 2026.1.03.5.4, 2025.11.2, 2025.12.1, 2026.1.0Patch availableCNA
  • discourse Vendordiscourse Affected before 3.5.4; 2025.11.0-latest to before 2025.11.2; 2025.12.0-latest to before 2025.12.1; 2026.1.0-latest to before 2026.1.0 Fixed in 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:*before 3.5.4; 2025.11.0 to before 2025.11.2Vulnerablediscourse
cpe:2.3:a:discourse:discourse:2025.12.0:*:*:*:stable:*:*:*2025.12.0Vulnerablediscourse
cpe:2.3:a:discourse:discourse:2026.1.0:*:*:*:stable:*:*:*2026.1.0Vulnerablediscourse
  • cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:* Versions before 3.5.4; 2025.11.0 to before 2025.11.2 Vulnerable ·discourse
  • cpe:2.3:a:discourse:discourse:2025.12.0:*:*:*:stable:*:*:* Versions 2025.12.0 Vulnerable ·discourse
  • cpe:2.3:a:discourse:discourse:2026.1.0:*:*:*:stable:*:*:* Versions 2026.1.0 Vulnerable ·discourse

Remediation

  • Fix · CNA discourse (discourse) Fixed in 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-23743

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