# Regular Expression Denial of Service in websocket-extensions (RubyGem)

Advisory record · `GHSA-g6wq-qcwm-j5g2`

- **Identifiers:** `GHSA-g6wq-qcwm-j5g2` · `CVE-2020-7663` · `SNYK-RUBY-WEBSOCKETEXTENSIONS-570830`
- **State:** Confirmed
- **Severity:** CVSS 8.2 High
- **Critical:** No
- **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 5 Jun 2020
- **Updated:** 8 Jul 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 5 Jun 2020, 14:21 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `websocket-extensions` (RubyGems): affected `<0.1.5`; fixed in `0.1.5`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 8.2 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** 0.046, the 91st percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 5 Jun 2020. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-g6wq-qcwm-j5g2](https://github.com/advisories/GHSA-g6wq-qcwm-j5g2)
- [OSV: GHSA-g6wq-qcwm-j5g2](https://osv.dev/vulnerability/GHSA-g6wq-qcwm-j5g2)
- <https://github.com/faye/websocket-extensions-ruby/security/advisories/GHSA-g6wq-qcwm-j5g2>
- <https://nvd.nist.gov/vuln/detail/CVE-2020-7663>
- <https://github.com/faye/websocket-extensions-ruby/commit/aa156a439da681361ed6f53f1a8131892418838b>
- <https://blog.jcoglan.com/2020/06/02/redos-vulnerability-in-websocket-extensions>
- <https://github.com/faye/websocket-extensions-ruby>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/websocket-extensions/CVE-2020-7663.yml>
- <https://lists.debian.org/debian-lts-announce/2020/08/msg00031.html>
- <https://snyk.io/vuln/SNYK-RUBY-WEBSOCKETEXTENSIONS-570830>
- <https://usn.ubuntu.com/4502-1>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-g6wq-qcwm-j5g2>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-g6wq-qcwm-j5g2/>. Everything for agents: <https://agentprime.io/llms.txt>.