GHSA-5m6q-g25r-mvwx — Forge has Denial of Service via Infinite Loop in BigInteger.modInverse() with Zero Input

Affected: npm: node-forge

## Summary

A Denial of Service (DoS) vulnerability exists in the node-forge library due to an infinite loop in the BigInteger.modInverse() function (inherited from the bundled jsbn library). When modInverse() is called with a zero value as input, the internal Extended Euclidean Algorithm enters an unreachable exit condition, causing the process to hang indefinitely and consume 100% CPU. Affected Package

Package name: node-forge (npm: node-forge) Repository: https://github.com/digitalbazaar/forge Affected versions: All versions (including latest) Affected file: lib/jsbn.js, function bnModInverse() Root cause component: Bundled copy of the jsbn (JavaScript Big Number) library

## Vulnerability Details

Type: Denial of Service (DoS) CWE: CWE-835 (Loop with Unreachable Exit Condition) Attack vector: Network (if the application processes untrusted input that reaches modInverse) Privileges required: None User interaction: None Impact: Availability (process hangs indefinitely) Suggested CVSS v3.1 score: 5.3–7.5 (depending on the context of usage)

## Root Cause Analysis

The BigInteger.prototype.modInverse(m) function in lib/jsbn.js implements the Extended Euclidean Algorithm to compute the modular multiplicative inverse of this modulo m. Mathematically, the modular inverse of 0 does not exist — gcd(0, m) = m ≠ 1 for any m > 1. However, the implementation does not check whether the input value is zero before entering the algorithm's main loop. When this equals 0, the algorithm's…

Most recent entries from all

GHSA-5m6q-g25r-mvwx — Forge has Denial of Service via Infinite Loop in BigInteger.modInverse() with Zero Input