Discourse: Topic featured link susceptible to stored XSS

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Summary

CVECVE-2026-55424
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-09 22:17:06 UTC
Updated2026-07-09 22:17:06 UTC
DescriptionDiscourse 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.

Risk And Classification

Primary CVSS: v4.0 7.4 HIGH from [email protected]

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:X/V:X/RE:X/U:X

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary7.4HIGHCVSS: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/C...
4.0CNADECLARED7.4HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
Low
User Interaction
Passive
Confidentiality
High
Integrity
High
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Discourse Discourse affected >= 2026.1.0-latest, < 2026.1.5 Not specified
CNA Discourse Discourse affected >= 2026.4.0-latest, < 2026.4.2 Not specified
CNA Discourse Discourse affected >= 2026.5.0-latest, < 2026.5.1 Not specified

References

ReferenceSourceLinkTags
github.com/discourse/discourse/commit/6679d9a5083488bae10c2adbb345c481c5... [email protected] github.com
github.com/discourse/discourse/releases/tag/v2026.5.1 [email protected] github.com
github.com/discourse/discourse/commit/6828aee9b15c2655d63b515ac919830bd5... [email protected] github.com
github.com/discourse/discourse/commit/1bce8881e4253d9bbab56f011a12ef899b... [email protected] github.com
github.com/discourse/discourse/security/advisories/GHSA-695w-7fv8-mxg3 [email protected] github.com
github.com/discourse/discourse/releases/tag/v2026.6.0 [email protected] github.com
github.com/discourse/discourse/releases/tag/v2026.1.5 [email protected] github.com
github.com/discourse/discourse/releases/tag/v2026.4.2 [email protected] github.com
github.com/discourse/discourse/commit/c9b9405f5bd0bf0269e505e28e3aad388d... [email protected] github.com
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