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Discourse: Stored HTML injection in video notification emails

Type: advisorySource: Official CVE ListRisk context updated1 source record

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.

Announced Source revision 2
Original source ↗
CVE context updated. The publisher announcement is unchanged.

CVE-2026-91120

Primary source · Revision 2

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-91120

discourse

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "discourse",
    "product": "discourse",
    "versions": [
      {
        "status": "affected",
        "version": "< 2026.8.0"
      },
      {
        "status": "affected",
        "version": ">= 2026.7.0-latest, < 2026.7.2"
      },
      {
        "status": "affected",
        "version": ">= 2026.6.0-latest, < 2026.6.3"
      },
      {
        "status": "affected",
        "version": ">= 2026.1.0-latest, < 2026.1.8"
      }
    ]
  }
]
Related CVEs
CVE-2026-91120

Source reference: /cveMetadata/cveId

Publisher severity

medium

Source reference: /containers/cna/metrics

Linked CVE context

These ratings describe the referenced vulnerabilities and products. They are not a severity rating for every application using this dependency.

CVE-2026-91120 · Medium

discourse

Event
#59640 · Revision 2
Added to Heist Feed
Publisher date
Read the original announcement