CVE-2026-9678: Undici Undici Vulnerable To Cross-user Information Vulnerability

MODERATE
Advisory Identifier: GHSA-pr7r-676h-xcf6
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CVSS 5.9
CWE-524
Published
Advisory Summary

CVE-2026-9678 is a MODERATE (CVSS 5.9) undici vulnerable to cross-user information vulnerability (CWE-524: Use of Cache Containing Sensitive Information) affecting Undici libraries in the npm ecosystem. The issue involves undici vulnerable to cross-user information disclosure via shared cache whitespace bypass. Remediation is available by upgrading affected packages to version 7.28.0, 8.5.0.

CVE-2026-9678 at a Glance

CVE Identifier CVE-2026-9678
GHSA Identifier GHSA-pr7r-676h-xcf6
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-524: Use of Cache Containing Sensitive Information
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-2026-9678

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: 7.28.0 
npm install undici@7.28.0
undici fixed: 8.5.0 
npm install undici@8.5.0
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-2026-9678, 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 7.28.0), 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-524: Use of Cache Containing Sensitive Information, where the code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere. 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 incorrectly classifies some responses as cacheable when the upstream `Cache-Control` header uses whitespace-padded qualified `private` or `no-cache` field names such as `private=" authorization"` or `no-cache="\tauthorization"`. The parser preserves the surrounding whitespace, so later comparisons against the literal `authorization` field name fail 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. Affected applications are those that explicitly enable the cache interceptor (`interceptors.cache()`) in shared mode, forward `Authorization` headers upstream, and receive cacheable responses with non-canonical qualified `private` or `no-cache` directives. ## Patches Upgrade to undici v7.28.0 or v8.5.0. ## 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-2026-9678 Affected Undici Versions

2 component(s)
Fixed Versions:
7.28.08.5.0
Product / Package Ecosystem Affected Versions Fixed Version
undici
npm/undici
npm
≥ 7.0.0
< 7.28.0
7.28.0
undici
npm/undici
npm
≥ 8.0.0
< 8.5.0
8.5.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nodejs/undici/security/advisories/GHSA-pr7r-676h-xcf6
NVD — CVE-2026-9678 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9678
Undici Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
Undici Source Repository REPOSITORY
https://github.com/nodejs/undici

Frequently Asked Questions

What is CVE-2026-9678?
CVE-2026-9678 is a security vulnerability in Undici involving undici vulnerable to cross-user information disclosure via shared cache whitespace bypass under CWE-524: Use of Cache Containing Sensitive Information.
Which Undici versions are affected?
Affected versions include releases prior to 7.28.0, 8.5.0 across affected packages: undici.
What version fixes CVE-2026-9678?
Upgrading to 7.28.0, 8.5.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is undici affected?
Yes, undici is affected in releases prior to 7.28.0, 8.5.0. Upgrade your dependency to 7.28.0, 8.5.0 or later.
What is the CVSS score of CVE-2026-9678?
CVE-2026-9678 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-2026-9678?
CVE-2026-9678 is classified under CWE-524: Use of Cache Containing Sensitive Information (The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.).
How can I check npm dependencies for CVE-2026-9678?
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-pr7r-676h-xcf6",
  "modified" : "2026-06-18T14:28:13Z",
  "published" : "2026-06-18T14:28:13Z",
  "aliases" : [ "CVE-2026-9678" ],
  "summary" : "undici vulnerable to cross-user information disclosure via shared cache whitespace bypass",
  "details" : "## Impact\n\nUndici's cache interceptor incorrectly classifies some responses as cacheable when the upstream `Cache-Control` header uses whitespace-padded qualified `private` or `no-cache` field names such as `private=\" authorization\"` or `no-cache=\"\\tauthorization\"`. The parser preserves the surrounding whitespace, so later comparisons against the literal `authorization` field name fail 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.\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 non-canonical qualified `private` or `no-cache` directives.\n\n## Patches\n\nUpgrade to undici v7.28.0 or v8.5.0.\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" : "7.28.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "undici"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.5.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/security/advisories/GHSA-pr7r-676h-xcf6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-9678"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nodejs/undici"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-524" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-18T14:28:13Z",
    "nvd_published_at" : "2026-06-17T18:18:06Z"
  }
}