CVE-2026-91120Public exploitNetwork attack vectorHinoki check available

Stored HTML injection via reparsed video titles

Published Sep 24, 2026 · Updated Sep 24, 2026

Stored HTML injection in Discourse before 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0 allows remote authenticated users to inject email content. The lazy-video email formatter inserted a provider title into a replacement HTML string, causing markup to be reparsed instead of retained as link text. A standard poster can reach this path when lazy video embeds are enabled, and HTML-capable mail clients can render the content without exposing a forum browser session.

CVSS severityUnavailable
Unscored
EPSS probability0.20%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Stored HTML injection in Discourse before 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0 allows remote authenticated users to inject email content. The lazy-video email formatter inserted a provider title into a replacement HTML string, causing markup to be reparsed instead of retained as link text. A standard poster can reach this path when lazy video embeds are enabled, and HTML-capable mail clients can render the content without exposing a forum browser session.

The record

CVE
CVE-2026-91120
Published
Sep 24, 2026
Updated
Sep 24, 2026
Vendor
Discourse
Product
Discourse
Classifications
Unavailable
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2026.1.0-latest, < 2026.1.8
  2. Affected versionversion=>= 2026.6.0-latest, < 2026.6.3
  3. Affected versionversion=>= 2026.7.0-latest, < 2026.7.2
  4. Affected versionversion=< 2026.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=>= 2026.1.0-latest, < 2026.1.8; version=>= 2026.6.0-latest, < 2026.6.3; version=>= 2026.7.0-latest, < 2026.7.2; version=< 2026.8.0

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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