High (7.5). EPSS 0.7% chance of exploitation in the next 30 days. Fixed in web3-utils 4.2.1.
Versions of the package web3-utils before 4.2.1 are vulnerable to Prototype Pollution via the utility functions format and mergeDeep, due to insecure recursive merge.
An attacker can manipulate an object's prototype, potentially leading to the alteration of the behavior of all objects inheriting from the affected prototype by passing specially crafted input to these functions.
Severity
CVSS 3.1
7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
0.7% chance of exploitation in the next 30 days; higher than 53% of CVEs (scores of 2026-10-31)