Medium severity · published Sep 21, 2026
CVE-2026-59830
Discourse: Stored XSS via unescaped actor name in post actions
5.4
CVSS
0.3%
EPSS
No
On KEV
Description
Discourse is an open-source discussion platform. Prior to 2026.7.0, the post action component failed to escape user-controlled display names before interpolating them into an HTML string passed to trustHTML. A user who could choose a crafted display name could persist markup in post action descriptions. Viewing the affected user activity streams could execute attacker-controlled script in another user's browser. This issue is fixed in version 2026.7.0.
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)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
discourse · discourse
< 2026.7.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59830
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59830
github.com
https://github.com/discourse/discourse/commit/dd786594ddd088657a7e6f9fefba5bd889965fe4
github.com
https://github.com/discourse/discourse/releases/tag/v2026.7.0
github.com
https://github.com/discourse/discourse/security/advisories/GHSA-x6mf-p7cg-69rw
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