Cross site scripting vulnerability with discussion titles
Flarum's page title system allowed for page titles to be converted into HTML DOM nodes when pages were rendered. The change was made after v1.5 and was not noticed.
This allowed an attacker to inject malicious HTML markup using a discussion title input, either by creating a new discussion or renaming one. The XSS attack occurs after a visitor opens the relevant discussion page.
Impact
All communities running Flarum from v1.5.0 to v1.6.1 are impacted.
Patches
The vulnerability has been fixed and published as flarum/core v1.6.2. All communities running Flarum from v1.5.0 to v1.6.1 have to upgrade as soon as possible to v1.6.2 using:
composer update --prefer-dist --no-dev -a -WYou can then confirm you run the latest version using:
composer show flarum/coreWorkarounds
None
For more information
For any questions or comments on this vulnerability please visit https://discuss.flarum.org/d/27558.
For support questions create a discussion at https://discuss.flarum.org/t/support.
A reminder that if you ever become aware of a security issue in Flarum, please report it to us privately by emailing security@flarum.org, and we will address it promptly.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | flarum/core | >= 1.5.0, < 1.6.2 | 1.6.2 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H- Weakness (CWE)
CWE-79- Platform
- Composer
- Package
flarum/core- Disclosed
- 21.11.2022
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-7x4w-j98p-854x - CC BY 4.0
Vulnerability history: flarum/core
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 9
- First → latest
- 06.2021 04.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 1
- Medium 5
- Low 1
Disclosures per year
- 2021: 1
- 2022: 1
- 2023: 4
- 2024: 1
- 2025: 1
- 2026: 1
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Cross site scripting vulnerability with discussion titles this entry
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