Cross-site Scripting (XSS) via topic titles when CSP disabled in Discourse

published 2025-02-04 21 mo ago modified 2026-09-08 2 mo ago also BIT-discourse-2024-53266 , EUVD-2024-51923 , GHSA-hw4j-4hg7-22h2

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits: 0; none known

Discourse is an open source platform for community discussion. In affected versions with some combinations of plugins, and with CSP disabled, activity streams in the user's profile page may be vulnerable to XSS. This has been patched in the latest version of Discourse core. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled.

Patch / fix

fixed in 2

bitnami discourse 3.3.3
discourse discourse 3.3.3, 3.4.0.beta4

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 21 mo ago (2025-02-04)

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
OSV	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
bitnami	discourse	<3.3.3	3.3.3

Affected products

discourse discourse

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /discourse/discourse/security/advisories/GHSA-hw4j-4hg7-22h2
third-party-advisory, advisory
nvd.nist.gov /vuln/detail/CVE-2024-53266
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary