CVE-2021-32640: Ws Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-6fc8-4gx4-v693
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CVSS 5.3
CWE-400 CWE-345
Published
Advisory Summary

CVE-2021-32640 is a MODERATE (CVSS 5.3) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Ws libraries in the npm ecosystem. The issue involves redos in sec-websocket-protocol header. Remediation is available by upgrading affected packages to version 7.4.6, 6.2.2, 5.2.3.

CVE-2021-32640 at a Glance

CVE Identifier CVE-2021-32640
GHSA Identifier GHSA-6fc8-4gx4-v693
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Ws
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2021-32640

To remediate this vulnerability, upgrade all affected Ws dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

ws fixed: 7.4.6 
npm install ws@7.4.6
ws fixed: 6.2.2 
npm install ws@6.2.2
ws fixed: 5.2.3 
npm install ws@5.2.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls ws

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-32640, inspect your project dependencies using npm:

npm ls ws

Analyze the terminal output to locate any version of Ws in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 7.4.6), your application is affected.

Note: The npm ls ws command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Ws, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact A specially crafted value of the `Sec-Websocket-Protocol` header can be used to significantly slow down a ws server. ### Proof of concept ```js for (const length of [1000, 2000, 4000, 8000, 16000, 32000]) { const value = 'b' + ' '.repeat(length) + 'x'; const start = process.hrtime.bigint(); value.trim().split(/ *, */); const end = process.hrtime.bigint(); console.log('length = %d, time = %f ns', length, end - start); } ``` ### Patches The vulnerability was fixed in ws@7.4.6 (https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff) and backported to ws@6.2.2 (https://github.com/websockets/ws/commit/78c676d2a1acefbc05292e9f7ea0a9457704bf1b) and ws@5.2.3 (https://github.com/websockets/ws/commit/76d47c1479002022a3e4357b3c9f0e23a68d4cd2). ### Workarounds 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. ### Credits The vulnerability was responsibly disclosed along with a fix in private by [Robert McLaughlin](https://github.com/robmcl4) from University of California, Santa Barbara.

CVE-2021-32640 Affected Ws Versions

3 component(s)
Fixed Versions:
7.4.66.2.25.2.3
Product / Package Ecosystem Affected Versions Fixed Version
ws
npm/ws
npm
≥ 7.0.0
< 7.4.6
7.4.6
ws
npm/ws
npm
≥ 6.0.0
< 6.2.2
6.2.2
ws
npm/ws
npm
≥ 5.0.0
< 5.2.3
5.2.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693
NVD — CVE-2021-32640 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-32640
Ws Source Repository REPOSITORY
https://github.com/websockets/ws/issues/1895
Security Fix Commit FIX COMMIT
https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff
Ws Source Repository REPOSITORY
https://github.com/websockets/ws
lists.apache.org/thread.html/rdfa7b6... WEB
https://lists.apache.org/thread.html/rdfa7b6253c4d6271e31566ecd5f30b7ce1b8fb2c89d52b8c4e0f4e30@%3Ccommits.tinkerpop.apache.org%3E
Ws Security Information SECURITY
https://security.netapp.com/advisory/ntap-20210706-0005

Frequently Asked Questions

What is CVE-2021-32640?
CVE-2021-32640 is a security vulnerability in Ws involving ReDoS in Sec-Websocket-Protocol header under CWE-400: Uncontrolled Resource Consumption.
Which Ws versions are affected?
Affected versions include releases prior to 7.4.6, 6.2.2, 5.2.3 across affected packages: ws.
What version fixes CVE-2021-32640?
Upgrading to 7.4.6, 6.2.2, 5.2.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is ws affected?
Yes, ws is affected in releases prior to 7.4.6, 6.2.2, 5.2.3. Upgrade your dependency to 7.4.6, 6.2.2, 5.2.3 or later.
What is the CVSS score of CVE-2021-32640?
CVE-2021-32640 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2021-32640?
CVE-2021-32640 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check npm dependencies for CVE-2021-32640?
Run the dependency tree command: 'npm ls ws'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6fc8-4gx4-v693",
  "modified" : "2021-10-06T22:05:51Z",
  "published" : "2021-05-28T19:19:03Z",
  "aliases" : [ "CVE-2021-32640" ],
  "summary" : "ReDoS in Sec-Websocket-Protocol header",
  "details" : "### Impact\n\nA specially crafted value of the `Sec-Websocket-Protocol` header can be used to significantly slow down a ws server.\n\n### Proof of concept\n\n```js\nfor (const length of [1000, 2000, 4000, 8000, 16000, 32000]) {\n  const value = 'b' + ' '.repeat(length) + 'x';\n  const start = process.hrtime.bigint();\n\n  value.trim().split(/ *, */);\n\n  const end = process.hrtime.bigint();\n\n  console.log('length = %d, time = %f ns', length, end - start);\n}\n```\n\n### Patches\n\nThe vulnerability was fixed in ws@7.4.6 (https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff) and backported to ws@6.2.2 (https://github.com/websockets/ws/commit/78c676d2a1acefbc05292e9f7ea0a9457704bf1b) and ws@5.2.3 (https://github.com/websockets/ws/commit/76d47c1479002022a3e4357b3c9f0e23a68d4cd2).\n\n### Workarounds\n\nIn 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.\n\n### Credits\n\nThe vulnerability was responsibly disclosed along with a fix in private by [Robert McLaughlin](https://github.com/robmcl4) from University of California, Santa Barbara.\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ws"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.0.0"
      }, {
        "fixed" : "7.4.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ws"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.0.0"
      }, {
        "fixed" : "6.2.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ws"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0"
      }, {
        "fixed" : "5.2.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-32640"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/websockets/ws/issues/1895"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/websockets/ws"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/rdfa7b6253c4d6271e31566ecd5f30b7ce1b8fb2c89d52b8c4e0f4e30@%3Ccommits.tinkerpop.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20210706-0005"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-345", "CWE-400" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-28T18:18:04Z",
    "nvd_published_at" : "2021-05-25T19:15:00Z"
  }
}