CVE-2026-105090: Auth Bypass

Description

Formbricks before 5.4.4 and 6 before 6.0.1 allows stored XSS. The survey-level Custom Head Scripts feature did not enforce the documented Manage permission boundary. A workspace member holding only readWrite permission could configure Custom Head Scripts on a survey, an operation the documentation restricts to the Manage role. Because the configured scripts execute in the authenticated browser session of any user who opens the affected survey, a lower-privileged member can run arbitrary JavaScript (stored cross-site scripting) in the session of higher-privileged users. Fixed versions require Manage access to modify survey Custom Head Scripts.

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Weakness Type (CWE)

CWE-863 Incorrect Authorization

References

Other References

https://github.com/formbricks/formbricks/pull/9432 https://github.com/formbricks/formbricks/releases/tag/5.4.4 https://github.com/formbricks/formbricks/releases/tag/6.0.1 https://www.sec4check.pl/blog/posts/cve-formbricks-broken-access-control-stored-xss-custom-head-scripts.html

Frequently Asked Questions

What is CVE-2026-105090? +

Formbricks before 5.4.4 and 6 before 6.0.1 allows stored XSS. The survey-level Custom Head Scripts feature did not enforce the documented Manage permission boundary. A workspace member holding only readWrite permission could configure Custom Head Scripts on a survey, an operation the documentation restricts to the Manage role. Because the configured scripts execute in the authenticated browser session of any user who opens the affected survey, a lower-privileged member can run arbitrary JavaScript (stored cross-site scripting) in the session of higher-privileged users. Fixed versions require Manage access to modify survey Custom Head Scripts.

How do I check if I'm vulnerable to CVE-2026-105090? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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