CVE-2026-85008: Undici Undici Vulnerable To Caching And Vulnerability

LOW
Advisory Identifier: GHSA-8436-99hf-9mmv
Share
CVSS 3.7
CWE-345
Published
Advisory Summary

CVE-2026-85008 is a LOW (CVSS 3.7) undici vulnerable to caching and vulnerability (CWE-345: Insufficient Verification of Data Authenticity) affecting Undici libraries in the npm ecosystem. The issue involves undici vulnerable to caching and replay of unsafe http method responses. Remediation is available by upgrading affected packages to version 7.29.1, 8.10.2.

CVE-2026-85008 at a Glance

CVE Identifier CVE-2026-85008
GHSA Identifier GHSA-8436-99hf-9mmv
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-345: Insufficient Verification of Data Authenticity
Affected Product Undici
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 3.7

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:L/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 None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-85008

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-2026-85008, 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-345: Insufficient Verification of Data Authenticity, where the product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. 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 `interceptors.cache()` documents that it caches only safe HTTP methods. However, its internal skip-list is built by subtracting the configured methods from the safe-methods set, so an unsafe method (`POST`, `PUT`, `PATCH`, `DELETE`) never lands in the skip-list and is looked up against the cache store. Combined with the storage gate (`canCacheResponse`) having no method check, a heuristically-cacheable response (for example a `404`) with an explicit `Cache-Control: max-age=...` to an unsafe method is stored and replayed on a subsequent identical request. The application's state-changing request never reaches the origin, and undici serves a fabricated response from the cache instead. This occurs with the default configuration (`methods: ['GET']`), which the public API does not allow widening to unsafe methods, so no application misuse is required; an untrusted origin can trigger it purely through its own response headers. ### Patches Upgrade to `7.29.1` or `8.10.2`. The cache interceptor no longer reads from or writes to the cache for unsafe HTTP methods, while still invalidating existing cache entries on successful unsafe requests. ### Workarounds None.

CVE-2026-85008 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

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
GitHub Advisory / Wiki ADVISORY
https://github.com/nodejs/undici/security/advisories/GHSA-8436-99hf-9mmv
NVD — CVE-2026-85008 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85008
Security Fix Commit FIX COMMIT
https://github.com/nodejs/undici/commit/2be07bf97b3022e0324142d31f99f6e019d815e3
Security Fix Commit FIX COMMIT
https://github.com/nodejs/undici/commit/b61d9432bac7caac51273ad209862e4c0bf935ae
Undici Security Information SECURITY
https://cna.openjsf.org/security-advisories.html

Frequently Asked Questions

What is CVE-2026-85008?
CVE-2026-85008 is a security vulnerability in Undici involving undici vulnerable to caching and replay of unsafe HTTP method responses under CWE-345: Insufficient Verification of Data Authenticity.
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-2026-85008?
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-2026-85008?
CVE-2026-85008 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-85008?
CVE-2026-85008 is classified under CWE-345: Insufficient Verification of Data Authenticity (The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.).
How can I check npm dependencies for CVE-2026-85008?
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-8436-99hf-9mmv",
  "modified" : "2026-09-29T18:16:28Z",
  "published" : "2026-09-29T18:16:28Z",
  "aliases" : [ "CVE-2026-85008" ],
  "summary" : "undici vulnerable to caching and replay of unsafe HTTP method responses",
  "details" : "### Impact\n\nundici's `interceptors.cache()` documents that it caches only safe HTTP methods. However, its internal skip-list is built by subtracting the configured methods from the safe-methods set, so an unsafe method (`POST`, `PUT`, `PATCH`, `DELETE`) never lands in the skip-list and is looked up against the cache store. Combined with the storage gate (`canCacheResponse`) having no method check, a heuristically-cacheable response (for example a `404`) with an explicit `Cache-Control: max-age=...` to an unsafe method is stored and replayed on a subsequent identical request. The application's state-changing request never reaches the origin, and undici serves a fabricated response from the cache instead. This occurs with the default configuration (`methods: ['GET']`), which the public API does not allow widening to unsafe methods, so no application misuse is required; an untrusted origin can trigger it purely through its own response headers.\n\n### Patches\n\nUpgrade to `7.29.1` or `8.10.2`. The cache interceptor no longer reads from or writes to the cache for unsafe HTTP methods, while still invalidating existing cache entries on successful unsafe requests.\n\n### Workarounds\n\nNone.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "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-8436-99hf-9mmv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-85008"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/commit/2be07bf97b3022e0324142d31f99f6e019d815e3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nodejs/undici/commit/b61d9432bac7caac51273ad209862e4c0bf935ae"
  }, {
    "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-345" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-29T18:16:28Z",
    "nvd_published_at" : "2026-09-04T17:17:02Z"
  }
}