What is the CVSS score of CVE-2026-30913?

CVE-2026-30913 has a CVSS 3.1 base score of 4.6 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Flarum are affected by CVE-2026-30913?

Organizations using Flarum should be aware of moderate risk from CVE-2026-30913, a cross-site scripting vulnerability rated CVSS 4.6.. A patch is available.

How to fix or mitigate CVE-2026-30913?

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

Flarum CVE-2026-30913

MEDIUM

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

2026-03-10 security-advisories@github.com

GHSA-3c4m-j3g4-hh25

XSS

4.6

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

4.6 MEDIUM

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

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

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

CVE Published

Mar 10, 2026 - 17:40 nvd

MEDIUM 4.6

DescriptionGitHub Advisory

Flarum is open-source forum software. When the flarum/nicknames extension is enabled, a registered user can set their nickname to a string that email clients interpret as a hyperlink. The nickname is inserted verbatim into plain-text notification emails, and recipients may be misled into visiting attacker-controlled domains.

AnalysisAI

Flarum's nicknames extension allows authenticated users to inject email-like hyperlinks into their nicknames, which are rendered verbatim in plain-text notification emails sent to other users. An attacker can exploit this to craft malicious nicknames that email clients interpret as clickable links, potentially redirecting recipients to attacker-controlled domains for phishing or credential harvesting. No patch is currently available for this vulnerability.

Technical ContextAI

Classified as CWE-79 (Cross-site Scripting (XSS)). Flarum is open-source forum software. When the flarum/nicknames extension is enabled, a registered user can set their nickname to a string that email clients interpret as a hyperlink. The nickname is inserted verbatim into plain-text notification emails, and recipients may be misled into visiting attacker-controlled domains.

Affected ProductsAI

Flarum is open-source forum software

RemediationAI

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