Vulnerability · Published Mar 9, 2026 · Assigned by GitHub_M

CVE-2026-30913flarum/nickname: Display name injection in notification emails (autolink & markdown)

Medium 4.6

In plain English

A medium-severity cross-site scripting in nicknames from flarum. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.6Medium

Exploit odds (30 days)0.2%top 90.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	flarum/nicknames	1.8.3	GHSA-3c4m-j3g4-hh25

Affected products (as reported)

Vendor	Product	Versions
flarum	nicknames	< 1.8.3

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

References

https://github.com/flarum/framework/security/advisories/GHSA-3c4m-j3g4-hh25 x_refsource_CONFIRM
https://github.com/flarum/nicknames/commit/4dde99729abdce8f6e2a7437c86e38735fdcca28 x_refsource_MISC
https://github.com/flarum/nicknames/releases/tag/v1.8. x_refsource_MISC