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CASL Ability is Vulnerable to Prototype Pollution

Critical severity GitHub Reviewed Published Feb 10, 2026 to the GitHub Advisory Database • Updated Feb 11, 2026

Package

npm @casl/ability (npm)

Affected versions

>= 2.4.0, <= 6.7.4

Patched versions

6.7.5

Description

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

References

Published by the National Vulnerability Database Feb 10, 2026
Published to the GitHub Advisory Database Feb 10, 2026
Reviewed Feb 11, 2026
Last updated Feb 11, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(6th percentile)

Weaknesses

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. Learn more on MITRE.

CVE ID

CVE-2026-1774

GHSA ID

GHSA-x9vf-53q3-cvx6

Source code

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