CVE-2026-123561
Published:November 08, 2026
Updated:November 09, 2026
devalue before 5.9.3 allows malformed null-prototype object keys to bypass parse's proto rejection through property-key coercion, an incomplete fix for GHSA-mwv9-gp5h-frr4. Attackers can supply crafted payloads that yield objects with a proto own property, which alone does not cause prototype pollution.
Affected Packages
https://github.com/sveltejs/devalue.git (GITHUB):
Affected version(s) >=v4.0.0 <v5.9.3 || >=v5.0.0 <v5.9.3Fix Suggestion:
Update to version v5.9.3devalue (NPM):
Affected version(s) >=4.0.0 <5.9.3 || >=5.0.0 <5.9.3Fix Suggestion:
Update to version 5.9.3Additional Notes
The description of this vulnerability differs from MITRE.
Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
3.7
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Improperly Controlled Modification of Object Prototype Attributes
EPSS
Base Score:
0.25