flarum/nickname: Display name injection in notification emails (autolink & markdown)
Priority MEDIUM 54CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00197 9th percentileScored 2026-11-07
Fix Fixed nicknames (flarum): 1.8.3flarum/nicknames (Packagist): 1.8.3
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| flarum | nicknames | before 1.8.3 | 1.8.3 | Patch available | CNA |
| — | flarum/nicknames (Packagist) | before 1.8.3 | 1.8.3 | Patch available | GHSA-3c4m-j3g4-hh25 |
- nicknames Vendorflarum Affected before 1.8.3 Fixed in 1.8.3 Patch available CNA
- flarum/nicknames (Packagist) Vendor— Affected before 1.8.3 Fixed in 1.8.3 Patch available GHSA-3c4m-j3g4-hh25
Remediation
- Fix · CNA nicknames (flarum) Fixed in 1.8.3
- Fix · GHSA-3c4m-j3g4-hh25 flarum/nicknames (Packagist) Fixed in 1.8.3 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-30913
- 2026-10-03 Alias added: GHSA-3c4m-j3g4-hh25
References
Other 5
- https://github.com/flarum/framework/security/advisories/GHSA-3c4m-j3g4-hh25
- https://github.com/flarum/nicknames/commit/4dde99729abdce8f6e2a7437c86e38735fdcca28
- https://github.com/flarum/nicknames/releases/tag/v1.8.
- https://github.com/flarum/framework
- https://github.com/flarum/nicknames/releases/tag/v1.8.3
More flarum vulnerabilities
- TI-2021-12339 XSS vulnerability with translator CVSS 3.1CRITICAL 10.0
- TI-2023-08736 Post mentions can be used to read any post on the forum without access control CVSS 3.1HIGH 7.7
- TI-2025-20573 Flarum Vulnerable to Session Hijacking via Authoritative Subdomain Cookie Overwrite CVSS 3.1MEDIUM 6.8
- TI-2026-30290 Flarum: Path traversal in LESS parser via theme color settings (incomplete fix for CVE-2023-27577) CVSS 3.1MEDIUM 4.9
- TI-2026-28792 Flarum < 1.8.16 Password Reset Token Expiry Bypass via POST /reset CVSS 4.0CRITICAL 9.2
- TI-2022-20279 Cross site scripting vulnerability with discussion titles in flarum CVSS 3.1CRITICAL 9.0
Sources
- CVE-2026-30913 · CVE Program
- CVE-2026-30913 · NVD
- FIRST EPSS
- GHSA-3c4m-j3g4-hh25 · GitHub Advisory Database · CC BY 4.0
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