---
id: CVE-2026-72722
title: Discourse is an open-source discussion platform
summary: >-
  Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2,
  2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for,
  and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see?
  checks…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-862
published: '2026-08-10'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:54:37.790'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-72722'
references:
  - url: >-
      https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a
    label: security-advisories@github.com
  - url: 'https://github.com/discourse/discourse/pull/42091'
    label: security-advisories@github.com
  - url: 'https://github.com/discourse/discourse/pull/42092'
    label: security-advisories@github.com
  - url: 'https://github.com/discourse/discourse/pull/42093'
    label: security-advisories@github.com
  - url: 'https://github.com/discourse/discourse/pull/42094'
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00442
epssPercentile: 0.35681
ingestedAt: '2026-09-08T21:11:12.273Z'
---

## Overview

Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.