Medium severity · published Jul 9, 2026
CVE-2026-55424
Discourse: Topic featured link susceptible to stored XSS
5.4
CVSS
0.4%
EPSS
No
On KEV
Description
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, a topic "featured link" was not sufficiently normalized and escaped before being rendered in the topic list, allowing a user who can set a featured link to inject JavaScript when default Content Security Policy protections were modified or disabled. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
discourse · discourse
>= 2026.1.0-latest, < 2026.1.5; >= 2026.4.0-latest, < 2026.4.2; >= 2026.5.0-latest, < 2026.5.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55424
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55424
Patch
https://github.com/discourse/discourse/commit/1bce8881e4253d9bbab56f011a12ef899b926b59
Patch
https://github.com/discourse/discourse/commit/6679d9a5083488bae10c2adbb345c481c583242c
Patch
https://github.com/discourse/discourse/commit/6828aee9b15c2655d63b515ac919830bd540ff83
Patch
https://github.com/discourse/discourse/commit/c9b9405f5bd0bf0269e505e28e3aad388d7657c5
Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.1.5
Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.4.2
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