CVE-2026-9496: Pacote Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-w4pp-8pjf-rmxw
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CVSS 7.5
CWE-400 CWE-1333
Published
Advisory Summary

CVE-2026-9496 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Pacote libraries in the npm ecosystem. The issue involves pacote is vulnerable to denial of service (dos) via the addgitsha function. Remediation is available by upgrading affected packages to version 21.5.1.

CVE-2026-9496 at a Glance

CVE Identifier CVE-2026-9496
GHSA Identifier GHSA-w4pp-8pjf-rmxw
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Pacote
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:H).

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 High (A:H)

How to Fix CVE-2026-9496

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

pacote fixed: 21.5.1 
npm install pacote@21.5.1
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 pacote

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-9496, inspect your project dependencies using npm:

npm ls pacote

Analyze the terminal output to locate any version of Pacote in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 21.5.1), your application is affected.

Note: The npm ls pacote 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 Pacote, 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

Versions of the package pacote from 11.2.7 are vulnerable to Denial of Service (DoS) via the addGitSha function. An attacker can exploit this vulnerability by supplying a specially crafted spec.rawSpec value that triggers the function’s regex replacement and string-manipulation logic, causing excessive CPU consumption and potentially stalling or crashing the process.

CVE-2026-9496 Affected Pacote Versions

1 component(s)
Fixed Versions:
21.5.1
Product / Package Ecosystem Affected Versions Fixed Version
pacote
npm/pacote
npm
≥ 11.2.7
< 21.5.1
21.5.1

References

NVD — CVE-2026-9496 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9496
Security Fix Commit FIX COMMIT
https://github.com/npm/pacote/commit/627a7dc1a214d857472a13b48e42559c75288c9e
Security Fix Commit FIX COMMIT
https://github.com/npm/pacote/commit/ce804fb1647fe1699b2f87efd01ea9f4efed8508
Pacote Source Repository REPOSITORY
https://github.com/npm/pacote
Pacote Source Repository REPOSITORY
https://github.com/npm/pacote/blob/9d7459440826ab4cf962ef98d8f3fd0c4d464b5c/lib/util/add-git-sha.js%23L2C1-L13C2
Pacote Release RELEASE
https://github.com/npm/pacote/releases/tag/v21.5.1
Pacote Release RELEASE
https://github.com/npm/pacote/releases/tag/v22.0.0
Pacote Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-16874025
Pacote Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JS-PACOTE-8225084

Frequently Asked Questions

What is CVE-2026-9496?
CVE-2026-9496 is a security vulnerability in Pacote involving pacote is vulnerable to Denial of Service (DoS) via the addGitSha function under CWE-400: Uncontrolled Resource Consumption.
Which Pacote versions are affected?
Affected versions include releases prior to 21.5.1 across affected packages: pacote.
What version fixes CVE-2026-9496?
Upgrading to 21.5.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pacote affected?
Yes, pacote is affected in releases prior to 21.5.1. Upgrade your dependency to 21.5.1 or later.
What is the CVSS score of CVE-2026-9496?
CVE-2026-9496 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-9496?
CVE-2026-9496 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-2026-9496?
Run the dependency tree command: 'npm ls pacote'. 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-w4pp-8pjf-rmxw",
  "modified" : "2026-08-27T16:39:41Z",
  "published" : "2026-05-26T13:30:54Z",
  "aliases" : [ "CVE-2026-9496" ],
  "summary" : "pacote is vulnerable to Denial of Service (DoS) via the addGitSha function",
  "details" : "Versions of the package pacote from 11.2.7 are vulnerable to Denial of Service (DoS) via the addGitSha function. An attacker can exploit this vulnerability by supplying a specially crafted spec.rawSpec value that triggers the function’s regex replacement and string-manipulation logic, causing excessive CPU consumption and potentially stalling or crashing the process.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "pacote"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.2.7"
      }, {
        "fixed" : "21.5.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-9496"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/pacote/commit/627a7dc1a214d857472a13b48e42559c75288c9e"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/pacote/commit/ce804fb1647fe1699b2f87efd01ea9f4efed8508"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/npm/pacote"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/pacote/blob/9d7459440826ab4cf962ef98d8f3fd0c4d464b5c/lib/util/add-git-sha.js%23L2C1-L13C2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/pacote/releases/tag/v21.5.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/pacote/releases/tag/v22.0.0"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-16874025"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JS-PACOTE-8225084"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1333", "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-27T16:39:41Z",
    "nvd_published_at" : "2026-05-26T07:16:19Z"
  }
}