CVE-2021-23438

Prototype Pollution

CRITICAL
9.8
CVSS Score
Published: September 1, 2021 at 06:20 PM UTC
Updated: June 17, 2026 at 03:38 AM UTC
1 product affected across 1 vendorMpath

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Severity
CRITICAL9.8
Exploit prediction
EPSS 2%

Description

This affects the package mpath before 0.8.4. A type confusion vulnerability can lead to a bypass of CVE-2018-16490. In particular, the condition ignoreProperties.indexOf(parts[i]) !== -1 returns -1 if parts[i] is ['__proto__']. This is because the method that has been called if the input is an array is Array.prototype.indexOf() and not String.prototype.indexOf(). They behave differently depending on the type of the input.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.8.4
Affected range stops below 0.8.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-843

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