CVE-2026-85014: Undici Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-rx4f-c7p8-82vq
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CVSS 5.9
CWE-754 CWE-248
Published
Advisory Summary

CVE-2026-85014 is a MODERATE (CVSS 5.9) denial of service vulnerability (CWE-754: Improper Check for Unusual or Exceptional Conditions) affecting Undici libraries in the npm ecosystem. The issue involves undici vulnerable to denial of service via websocketstream unclean close. Remediation is available by upgrading affected packages to version 7.29.1, 8.10.2.

CVE-2026-85014 at a Glance

CVE Identifier CVE-2026-85014
GHSA Identifier GHSA-rx4f-c7p8-82vq
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-754: Improper Check for Unusual or Exceptional Conditions
Affected Product Undici
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.9

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

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

How to Fix CVE-2026-85014

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

undici fixed: 7.29.1 
npm install undici@7.29.1
undici fixed: 8.10.2 
npm install undici@8.10.2
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 undici

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-85014, inspect your project dependencies using npm:

npm ls undici

Analyze the terminal output to locate any version of Undici in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 7.29.1), your application is affected.

Note: The npm ls undici 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-754: Improper Check for Unusual or Exceptional Conditions, where the product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product. In Undici, 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 undici's `WebSocketStream` crashes the client process when a WebSocket connection is closed abruptly without a close handshake. On such an unclean close, the internal socket-close handler calls `abort()` on the writable stream even when the application holds a writer lock. Per the WHATWG Streams standard, aborting a locked stream returns a promise that rejects with a `TypeError`, and the handler discards that promise. The unobserved rejection surfaces as an `unhandledRejection` and, under Node.js's default behavior, terminates the process. A malicious or compromised WebSocket server can crash a client with a single connection teardown (a TCP reset, a proxy teardown, or a protocol-violating frame). Affected applications are those using the `WebSocketStream` API and writing through a writer, which is the standard way to write. All releases from undici 7.0.0 are affected. WebSocketStream was introduced in 7.0.0. ## Patches Upgrade to undici v7.29.1 or v8.10.2. ## Workarounds No workaround is available.

CVE-2026-85014 Affected Undici Versions

2 component(s)
Fixed Versions:
7.29.18.10.2
Product / Package Ecosystem Affected Versions Fixed Version
undici
npm/undici
npm
≥ 7.0.0
< 7.29.1
7.29.1
undici
npm/undici
npm
≥ 8.0.0
< 8.10.2
8.10.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nodejs/undici/security/advisories/GHSA-rx4f-c7p8-82vq
NVD — CVE-2026-85014 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85014
Security Fix Commit FIX COMMIT
https://github.com/nodejs/undici/commit/1858656ebb1e919311c1f31613dfd581b7214349
Security Fix Commit FIX COMMIT
https://github.com/nodejs/undici/commit/662d0ea671fe64139e79533c913fce412765e1d7
Undici Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
Undici Source Repository REPOSITORY
https://github.com/nodejs/undici
Undici Release RELEASE
https://github.com/nodejs/undici/releases/tag/v7.29.1
Undici Release RELEASE
https://github.com/nodejs/undici/releases/tag/v8.10.2

Frequently Asked Questions

What is CVE-2026-85014?
CVE-2026-85014 is a security vulnerability in Undici involving undici vulnerable to Denial of Service via WebSocketStream unclean close under CWE-754: Improper Check for Unusual or Exceptional Conditions.
Which Undici versions are affected?
Affected versions include releases prior to 7.29.1, 8.10.2 across affected packages: undici.
What version fixes CVE-2026-85014?
Upgrading to 7.29.1, 8.10.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is undici affected?
Yes, undici is affected in releases prior to 7.29.1, 8.10.2. Upgrade your dependency to 7.29.1, 8.10.2 or later.
What is the CVSS score of CVE-2026-85014?
CVE-2026-85014 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-85014?
CVE-2026-85014 is classified under CWE-754: Improper Check for Unusual or Exceptional Conditions (The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.).
How can I check npm dependencies for CVE-2026-85014?
Run the dependency tree command: 'npm ls undici'. 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-rx4f-c7p8-82vq",
  "modified" : "2026-09-29T18:10:32Z",
  "published" : "2026-09-29T18:10:32Z",
  "aliases" : [ "CVE-2026-85014" ],
  "summary" : "undici vulnerable to Denial of Service via WebSocketStream unclean close",
  "details" : "## Impact\n\nundici's `WebSocketStream` crashes the client process when a WebSocket connection is closed abruptly without a close handshake. On such an unclean close, the internal socket-close handler calls `abort()` on the writable stream even when the application holds a writer lock. Per the WHATWG Streams standard, aborting a locked stream returns a promise that rejects with a `TypeError`, and the handler discards that promise. The unobserved rejection surfaces as an `unhandledRejection` and, under Node.js's default behavior, terminates the process.\n\nA malicious or compromised WebSocket server can crash a client with a single connection teardown (a TCP reset, a proxy teardown, or a protocol-violating frame). Affected applications are those using the `WebSocketStream` API and writing through a writer, which is the standard way to write.\n\nAll releases from undici 7.0.0 are affected. WebSocketStream was introduced in 7.0.0.\n\n## Patches\n\nUpgrade to undici v7.29.1 or v8.10.2.\n\n## Workarounds\n\nNo workaround is available.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "undici"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.0.0"
      }, {
        "fixed" : "7.29.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "undici"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.10.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/security/advisories/GHSA-rx4f-c7p8-82vq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-85014"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/commit/1858656ebb1e919311c1f31613dfd581b7214349"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/commit/662d0ea671fe64139e79533c913fce412765e1d7"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nodejs/undici"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/releases/tag/v7.29.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/releases/tag/v8.10.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-248", "CWE-754" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-29T18:10:32Z",
    "nvd_published_at" : "2026-09-04T17:17:02Z"
  }
}