---
id: CVE-2026-91120
title: Discourse is an open-source discussion platform
summary: >-
  Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3,
  2026.7.2, and 2026.8.0, provider-controlled video titles in lazy video embeds
  could be reparsed as HTML when Discourse generated notification emails or chat
  su…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: discourse
product: discourse
affected:
  - discourse < 2026.8.0
  - 'discourse >= 2026.7.0-latest, < 2026.7.2'
  - 'discourse >= 2026.6.0-latest, < 2026.6.3'
  - 'discourse >= 2026.1.0-latest, < 2026.1.8'
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T18:19:06.540'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91120'
references:
  - url: >-
      https://github.com/discourse/discourse/commit/6bf1cdcb3ae1aa146e1fd953a62046bf4a1f143f
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/commit/8338919df4ecbd0fb85314b762772cc033b764e3
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/commit/e7de8285203a2edf85beff3b951e66aeb7e5dc76
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/commit/ed8b47df80bcc9f0bd70773fc399c9386f9d52dd
    label: security-advisories@github.com
  - url: 'https://github.com/discourse/discourse/pull/42882'
    label: security-advisories@github.com
  - url: >-
      https://github.com/discourse/discourse/security/advisories/GHSA-h7cg-2vww-m45c
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-24T17:24:51.329319Z'
ingestedAt: '2026-09-24T17:48:30.405Z'
---

## Overview

Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, provider-controlled video titles in lazy video embeds could be reparsed as HTML when Discourse generated notification emails or chat summaries. A user with standard posting privileges could create a post for an enabled YouTube, Vimeo, or TikTok provider whose title contained markup, and the email and chat-summary rendering path would place that markup into the output instead of treating it solely as text. Recipients using HTML-capable email clients could see injected content, potentially including event handlers, but the issue did not directly expose a Discourse browser session or affect the forum page itself. Lazy video embeds must be enabled, which is the default configuration. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.

## Remediation

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