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No exploitation reportedFix available

CVE-2021-32640

No exploitation reported by the sources we read.

  • Published2021-05-25
  • Fixed in7.4.6 · 6.2.2 · 5.2.3
  • WeaknessCWE-400

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-05-2519:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-32640?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-32640?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Ws project ws
BranchAffectedFixed in
7.x≥ 7.0.0, < 7.4.67.4.6
6.2≥ 5.0.0, < 6.2.26.2.2
6.x≥ 6.0.0, < 6.2.26.2.2
5.x≥ 5.0.0, < 5.2.35.2.3
Netapp e-series performance analyzer
BranchAffectedFixed in
—all versionsno fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • @rootio/wsRoot:npmall versions · fixed in 7.4.6-root.io.1
  • @rootio/wsRoot:npmall versions · fixed in 5.2.3-root.io.1
  • @rootio/wsRoot:npmall versions · fixed in 6.2.2-root.io.1
  • @rootio/wsRoot:npmall versions · fixed in 6.2.2-root.io.2
  • @rootio/wsRoot:npmall versions · fixed in 7.4.6-root.io.2
  • js-jqueryAzure Linux:3all versions · no fixed version listed
  • node-wsUbuntu:22.04:LTSall versions · no fixed version listed
  • node-wsUbuntu:20.04:LTSall versions · no fixed version listed

15 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-32640 Red Hat Product Security23 known affected

    nodejs-ws: Specially crafted value of the `Sec-Websocket-Protocol` header can be used to significantly slow down a ws server

    servicemesh-grafana as a component of OpenShift Service Mesh 2.0 · servicemesh-grafana-prometheus as a component of OpenShift Service Mesh 2.0 · servicemesh-grafana.src as a component of OpenShift Service Mesh 2.0 · +20 more

Full record on NVD

Fix

  1. Update Ws project ws to 7.4.6 · 6.2.2 · 5.2.3
  2. Workaround from the vendor Red Hat Product Security CVE-2021-32640 · 23 productsIn 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 and/or the maxHeaderSize options.
  3. No fix available, says the vendor Red Hat Product Security CVE-2021-32640 · 16 productsFix deferred
  4. No fix available, says the vendor Red Hat Product Security CVE-2021-32640 · 7 productsAffected

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.15.3known since 2026-10-23
  • NVDCVSS 3.15.3read 2026-10-23
  • NVDCVSS 2.05read 2026-10-23
  • CNAweakness (CWE)CWE-400known since 2026-10-23
  • NVDweakness (CWE)CWE-400read 2026-10-23
  • FIRST EPSSEPSS score2.8 %2026-11-03
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryMODERATE2021-05-28

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Published
2021-05-25
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-6fc8-4gx4-v693

Frequently asked questions

What is CVE-2021-32640?

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.

Is CVE-2021-32640 actively exploited?

Active exploitation of CVE-2021-32640 has not been confirmed. Its EPSS score was 2.8% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-32640?

CVE-2021-32640 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

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