What is the CVSS score of CVE-2026-27154?

CVE-2026-27154 has a CVSS 3.1 base score of 6.1 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Discourse are affected by CVE-2026-27154?

Organizations using Discourse should be aware of moderate risk from CVE-2026-27154, a cross-site scripting vulnerability rated CVSS 6.1.

How to fix or mitigate CVE-2026-27154?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Discourse CVE-2026-27154

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-02-26 security-advisories@github.com

XSS Discourse

6.1

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.1 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:56 vuln.today

CVE Published

Feb 26, 2026 - 22:20 nvd

MEDIUM 6.1

DescriptionGitHub Advisory

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, a user full name can be evaluated as raw HTML when the following settings are set: display_name_on_posts => true; and prioritize_username_in_ux => false. Editing a post of a malicious user would trigger an XSS. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

AnalysisAI

Stored cross-site scripting in Discourse allows attackers to inject malicious HTML through user full names when specific display settings are enabled, which executes in the browsers of users viewing or editing affected posts. The vulnerability requires the display_name_on_posts setting to be true and prioritize_username_in_ux to be false, potentially affecting installations with these configurations. No patch is currently available, and users should disable the vulnerable display settings or upgrade to patched versions 2025.12.2, 2026.1.1, or 2026.2.0.

Technical ContextAI

Classified as CWE-79 (Cross-site Scripting (XSS)). Affects Discourse. Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, a user full name can be evaluated as raw HTML when the following settings are set: display_name_on_posts => true; and prioritize_username_in_ux => false. Editing a post of a malicious user would trigger an XSS. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

RemediationAI

Monitor vendor advisories for a patch. Implement output encoding and Content Security Policy headers. Restrict network access to the affected service where possible.