Vulnerabilities in pkg:npm/@casl/ability

PACKAGE
Advisory Identifier: GHSA-x9vf-53q3-cvx6
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Advisory Summary

CVE-2026-1774 is a CRITICAL (CVSS 9.8) casl ability is vulnerable to vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting @casl/ability libraries in the npm ecosystem. The issue involves casl ability is vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 6.7.5.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/@casl/ability

1 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/@casl/ability. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-x9vf-53q3-cvx6 CVE-2026-1774 CRITICAL CASL Ability is Vulnerable to Prototype Pollution

CVE-2026-1774 at a Glance

CVE Identifier CVE-2026-1774
GHSA Identifier GHSA-x9vf-53q3-cvx6
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product @casl/ability
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.8

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:H/I:H/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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-1774

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

@casl/ability fixed: 6.7.5 
npm install @casl/ability@6.7.5
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 @casl/ability

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-1774, inspect your project dependencies using npm:

npm ls @casl/ability

Analyze the terminal output to locate any version of @casl/ability in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.7.5), your application is affected.

Note: The npm ls @casl/ability 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-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In @casl/ability, 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

CASL Ability, versions 2.4.0 through 6.7.4, contains a prototype pollution vulnerability.

CVE-2026-1774 Affected @casl/ability Versions

1 component(s)
Fixed Versions:
6.7.5
Product / Package Ecosystem Affected Versions Fixed Version
@casl/ability
npm/@casl/ability
npm
≥ 2.4.0
< 6.7.5
6.7.5

References

NVD — CVE-2026-1774 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-1774
@casl/ability Source Repository REPOSITORY
https://github.com/stalniy/casl/pull/1093
Security Fix Commit FIX COMMIT
https://github.com/stalniy/casl/commit/39da920ec1dfadf3655e28bd0389e960ac6871f4
MITRE CVE Database — CVE-2026-1774 MITRE
https://cwe.mitre.org/data/definitions/1321.html
@casl/ability Security Information SECURITY
https://developer.mozilla.org/en-US/docs/Web/Security/Attacks/Prototype_pollution
@casl/ability Source Repository REPOSITORY
https://github.com/stalniy/casl
@casl/ability Source Repository REPOSITORY
https://github.com/stalniy/casl/tree/master/packages/casl-ability
www.kb.cert.org/vuls/id/458422 WEB
https://www.kb.cert.org/vuls/id/458422

Frequently Asked Questions

What is CVE-2026-1774?
CVE-2026-1774 is a security vulnerability in @casl/ability involving CASL Ability is Vulnerable to Prototype Pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which @casl/ability versions are affected?
Affected versions include releases prior to 6.7.5 across affected packages: @casl/ability.
What version fixes CVE-2026-1774?
Upgrading to 6.7.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @casl/ability affected?
Yes, @casl/ability is affected in releases prior to 6.7.5. Upgrade your dependency to 6.7.5 or later.
What is the CVSS score of CVE-2026-1774?
CVE-2026-1774 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-1774?
CVE-2026-1774 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-1774?
Run the dependency tree command: 'npm ls @casl/ability'. 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-x9vf-53q3-cvx6",
  "modified" : "2026-02-11T19:09:05Z",
  "published" : "2026-02-10T18:30:38Z",
  "aliases" : [ "CVE-2026-1774" ],
  "summary" : "CASL Ability is Vulnerable to Prototype Pollution",
  "details" : "CASL Ability, versions 2.4.0 through 6.7.4, contains a prototype pollution vulnerability.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@casl/ability"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.4.0"
      }, {
        "fixed" : "6.7.5"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 6.7.4"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-1774"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/stalniy/casl/pull/1093"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/stalniy/casl/commit/39da920ec1dfadf3655e28bd0389e960ac6871f4"
  }, {
    "type" : "WEB",
    "url" : "https://cwe.mitre.org/data/definitions/1321.html"
  }, {
    "type" : "WEB",
    "url" : "https://developer.mozilla.org/en-US/docs/Web/Security/Attacks/Prototype_pollution"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/stalniy/casl"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/stalniy/casl/tree/master/packages/casl-ability"
  }, {
    "type" : "WEB",
    "url" : "https://www.kb.cert.org/vuls/id/458422"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-11T19:09:05Z",
    "nvd_published_at" : "2026-02-10T16:16:10Z"
  }
}