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Vulnerability record · CVE-2026-55424 · published 9 July 2026

CVE-2026-55424: Discourse cross-site scripting vulnerability

Discourse · Discourse

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.

7.4 CVSS 4.0 High EPSS 0.42% · top 66.8% CWE-79 · Cross-site scripting
7.4CVSS 4.0 base score
0.42%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
9References
14 Jul 2026Last modified by NVD

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:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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 Patch
https://github.com/discourse/discourse/releases/tag/v2026.1.5 Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.4.2 Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.5.1 Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.6.0 Release Notes
https://github.com/discourse/discourse/security/advisories/GHSA-695w-7fv8-mxg3 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-55424), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.