Review reviewHigh

CVE-2026-55424

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.

CVSS: 7.4
EPSS: 0.27%
CISA KEV: Not listed
Published: 2026.07.10

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.27%

Technical severityCVSS 7.4

Vulnerability overview

Affected product and versions

Product: discourse
Affected versions: >= >= 2026.1.0-latest, < 2026.1.5, >= >= 2026.4.0-latest, < 2026.4.2, >= >= 2026.5.0-latest, < 2026.5.1, >= 2026.1.0 < 2026.1.5, >= 2026.4.0 < 2026.4.2, >= 2026.5.0 < 2026.5.1, 2026.6.0
Fixed versions: 2026.1.5, 2026.4.2, 2026.5.1

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that discourse and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: 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
CWE: CWE-79