{"cve":"CVE-2020-7663","nvd":{"published":"2020-06-02T19:15:12.467","modified":"2026-06-17T03:25:13.380","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":[],"references":["https://blog.jcoglan.com/2020/06/02/redos-vulnerability-in-websocket-extensions","https://github.com/faye/websocket-extensions-ruby/commit/aa156a439da681361ed6f53f1a8131892418838b","https://github.com/faye/websocket-extensions-ruby/security/advisories/GHSA-g6wq-qcwm-j5g2","https://lists.debian.org/debian-lts-announce/2020/08/msg00031.html","https://snyk.io/vuln/SNYK-RUBY-WEBSOCKETEXTENSIONS-570830"],"products":["canonical:ubuntu_linux","debian:debian_linux","websocket-extensions_project:websocket-extensions"],"source":"nvd","synced_at":"2026-10-19T21:05:42.039641217+00:00"},"epss":{"cve":"CVE-2020-7663","score":0.04639,"percentile":0.91721,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-g6wq-qcwm-j5g2","url":"https://osv.dev/vulnerability/GHSA-g6wq-qcwm-j5g2","summary":"Regular Expression Denial of Service in websocket-extensions (RubyGem)","modified":"2026-07-08T06:50:03.986630807Z","packages":[{"ecosystem":"RubyGems","name":"websocket-extensions","purl":"pkg:gem/websocket-extensions","ranges":["<0.1.5"],"fixed":["0.1.5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}