CVE-2026-33411Network attack vector

Stored XSS in solved-stream topic titles

Published Mar 20, 2026 · Updated Mar 20, 2026

Stored XSS in Discourse solved-post streams allows remote authenticated users to execute script through crafted topic titles. Discourse has not published which renderer fails to neutralize the title before inserting it into the solved-post stream. Exploitation requires an account able to create or rename an affected topic; executed script can read or alter data available to the affected browser session.

CVSS severity5.4
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in Discourse solved-post streams allows remote authenticated users to execute script through crafted topic titles. Discourse has not published which renderer fails to neutralize the title before inserting it into the solved-post stream. Exploitation requires an account able to create or rename an affected topic; executed script can read or alter data available to the affected browser session.

The record

CVE
CVE-2026-33411
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
Discourse
Product
Discourse
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 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, < 2026.1.2
  2. Affected versionversion=>= 2026.2.0-latest, < 2026.2.1
  3. Affected versionversion== 2026.3.0-latest

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Discourse · Discourseversion=>= 2026.1.0-latest, < 2026.1.2; version=>= 2026.2.0-latest, < 2026.2.1; version== 2026.3.0-latest

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo