Vulnerability · Published Sep 21, 2026 · Assigned by GitHub_M

CVE-2026-59830Discourse: Stored XSS via unescaped actor name in post actions

Medium 5.4

In plain English

A medium-severity cross-site scripting in discourse from discourse. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).

Severity (CVSS 3.1)5.4Medium

Exploit odds (30 days)0.3%top 78.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
discourse	discourse	< 2026.7.0

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References

https://github.com/discourse/discourse/security/advisories/GHSA-x6mf-p7cg-69rw x_refsource_CONFIRM
https://github.com/discourse/discourse/commit/dd786594ddd088657a7e6f9fefba5bd889965fe4 x_refsource_MISC
https://github.com/discourse/discourse/releases/tag/v2026.7.0 x_refsource_MISC