{"cve":"CVE-2021-32640","nvd":{"published":"2021-05-25T19:15:07.767","modified":"2026-06-17T03:53:19.733","status":"Modified","description":"ws is an open source WebSocket client and server library for Node.js. A specially crafted value of the `Sec-Websocket-Protocol` header can be used to significantly slow down a ws server. The vulnerability has been fixed in ws@7.4.6 (https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff). In vulnerable versions of ws, the issue can be mitigated by reducing the maximum allowed length of the request headers using the [`--max-http-header-size=size`](https://nodejs.org/api/cli.html#cli_max_http_header_size_size) and/or the [`maxHeaderSize`](https://nodejs.org/api/http.html#http_http_createserver_options_requestlistener) options.","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:L","score":5.3},"cwes":["CWE-400"],"references":["https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff","https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693","https://lists.apache.org/thread.html/rdfa7b6253c4d6271e31566ecd5f30b7ce1b8fb2c89d52b8c4e0f4e30%40%3Ccommits.tinkerpop.apache.org%3E","https://security.netapp.com/advisory/ntap-20210706-0005/","https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff"],"products":["netapp:e-series_performance_analyzer","ws_project:ws"],"source":"nvd","synced_at":"2026-10-19T21:18:09.669877188+00:00"},"epss":{"cve":"CVE-2021-32640","score":0.02821,"percentile":0.8658,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-6fc8-4gx4-v693","url":"https://osv.dev/vulnerability/GHSA-6fc8-4gx4-v693","summary":"ReDoS in Sec-Websocket-Protocol header","modified":"2026-07-08T06:28:00.103808643Z","packages":[{"ecosystem":"npm","name":"ws","purl":"pkg:npm/ws","ranges":[">=7.0.0 <7.4.6"],"fixed":["7.4.6"]},{"ecosystem":"npm","name":"ws","purl":"pkg:npm/ws","ranges":[">=6.0.0 <6.2.2"],"fixed":["6.2.2"]},{"ecosystem":"npm","name":"ws","purl":"pkg:npm/ws","ranges":[">=5.0.0 <5.2.3"],"fixed":["5.2.3"]}]}],"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."]}