CVE-2026-14643: Undici Undici Vulnerable To Cross-user Information Vulnerability

MODERATE
Advisory Identifier: GHSA-jr45-8vmc-qm54
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CVSS 5.9
CWE-436 CWE-524
Published
Advisory Summary

CVE-2026-14643 is a MODERATE (CVSS 5.9) undici vulnerable to cross-user information vulnerability (CWE-436: Interpretation Conflict) affecting Undici libraries in the npm ecosystem. The issue involves undici vulnerable to cross-user information disclosure via whitespace around equals in cache-control directives. Remediation is available by upgrading affected packages to version 7.29.0, 8.9.0.

CVE-2026-14643 at a Glance

CVE Identifier CVE-2026-14643
GHSA Identifier GHSA-jr45-8vmc-qm54
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-436: Interpretation Conflict
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:H/I:N/A:N).

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 High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-14643

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: 7.29.0 
npm install undici@7.29.0
undici fixed: 8.9.0 
npm install undici@8.9.0
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-2026-14643, 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 7.29.0), 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-436: Interpretation Conflict, where product a handles inputs or steps differently than product b, which causes a to perform incorrect actions based on its perception of b's state. 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 cache interceptor mishandles optional whitespace (OWS) placed around the `=` of a qualified `no-cache` or `private` Cache-Control directive, such as `no-cache ="authorization"` (OWS before `=`) or `no-cache= "authorization"` (OWS after `=`). The parser either drops the directive entirely or stores a field name with literal quote characters, so the downstream cache decisions do not recognize the qualification and the response is stored. In shared-cache mode, this allows a response containing one user's authenticated data to be served from cache to a subsequent caller, including an unauthenticated caller, when both requests resolve to the same cache key. The impact class is identical to CVE-2026-9678 (GHSA-pr7r-676h-xcf6); this advisory covers the whitespace-around-`=` bypass that the earlier fix did not normalize. Affected applications are those that explicitly enable the cache interceptor (`interceptors.cache()`) in shared mode, forward `Authorization` headers upstream, and receive cacheable responses with qualified `private` or `no-cache` directives whose field-name list is padded with OWS around the `=`. ## Patches Upgrade to undici v7.29.0 or v8.9.0. ## Workarounds If upgrade is not immediately possible, disable shared-cache mode for traffic that includes `Authorization` headers, avoid caching responses to authenticated requests, or add `Vary: Authorization` upstream.

CVE-2026-14643 Affected Undici Versions

2 component(s)
Fixed Versions:
7.29.08.9.0
Product / Package Ecosystem Affected Versions Fixed Version
undici
npm/undici
npm
≥ 7.0.0
< 7.29.0
7.29.0
undici
npm/undici
npm
≥ 8.0.0
< 8.9.0
8.9.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nodejs/undici/security/advisories/GHSA-jr45-8vmc-qm54
NVD — CVE-2026-14643 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-14643
Security Fix Commit FIX COMMIT
https://github.com/nodejs/undici/commit/85a240551c9feb8b8a0ecc56c84b2b3015add8a9
Undici Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
Security Fix Commit FIX COMMIT
https://github.com/nodejs/undici/commit/cb105d7c79069150982fa11acada0dd94a60dbbc
Undici Source Repository REPOSITORY
https://github.com/nodejs/undici
Undici Release RELEASE
https://github.com/nodejs/undici/releases/tag/v7.29.0
Undici Release RELEASE
https://github.com/nodejs/undici/releases/tag/v8.9.0

Frequently Asked Questions

What is CVE-2026-14643?
CVE-2026-14643 is a security vulnerability in Undici involving undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives under CWE-436: Interpretation Conflict.
Which Undici versions are affected?
Affected versions include releases prior to 7.29.0, 8.9.0 across affected packages: undici.
What version fixes CVE-2026-14643?
Upgrading to 7.29.0, 8.9.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is undici affected?
Yes, undici is affected in releases prior to 7.29.0, 8.9.0. Upgrade your dependency to 7.29.0, 8.9.0 or later.
What is the CVSS score of CVE-2026-14643?
CVE-2026-14643 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:H/I:N/A:N.
What CWE is associated with CVE-2026-14643?
CVE-2026-14643 is classified under CWE-436: Interpretation Conflict (Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.).
How can I check npm dependencies for CVE-2026-14643?
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-jr45-8vmc-qm54",
  "modified" : "2026-08-03T19:32:12Z",
  "published" : "2026-08-03T19:32:12Z",
  "aliases" : [ "CVE-2026-14643" ],
  "summary" : "undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives",
  "details" : "## Impact\n\nUndici's cache interceptor mishandles optional whitespace (OWS) placed around the `=` of a qualified `no-cache` or `private` Cache-Control directive, such as `no-cache =\"authorization\"` (OWS before `=`) or `no-cache= \"authorization\"` (OWS after `=`). The parser either drops the directive entirely or stores a field name with literal quote characters, so the downstream cache decisions do not recognize the qualification and the response is stored.\n\nIn shared-cache mode, this allows a response containing one user's authenticated data to be served from cache to a subsequent caller, including an unauthenticated caller, when both requests resolve to the same cache key. The impact class is identical to CVE-2026-9678 (GHSA-pr7r-676h-xcf6); this advisory covers the whitespace-around-`=` bypass that the earlier fix did not normalize.\n\nAffected applications are those that explicitly enable the cache interceptor (`interceptors.cache()`) in shared mode, forward `Authorization` headers upstream, and receive cacheable responses with qualified `private` or `no-cache` directives whose field-name list is padded with OWS around the `=`.\n\n## Patches\n\nUpgrade to undici v7.29.0 or v8.9.0.\n\n## Workarounds\n\nIf upgrade is not immediately possible, disable shared-cache mode for traffic that includes `Authorization` headers, avoid caching responses to authenticated requests, or add `Vary: Authorization` upstream.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "undici"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.0.0"
      }, {
        "fixed" : "7.29.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "undici"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.9.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/security/advisories/GHSA-jr45-8vmc-qm54"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-14643"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/commit/85a240551c9feb8b8a0ecc56c84b2b3015add8a9"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/commit/cb105d7c79069150982fa11acada0dd94a60dbbc"
  }, {
    "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/v7.29.0"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/releases/tag/v8.9.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-436", "CWE-524" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-03T19:32:12Z",
    "nvd_published_at" : "2026-07-29T22:16:52Z"
  }
}