CVE-2026-118781: Forge: Denial of Service via infinite loop in BigInteger.modInverse() with negative input (incomplete fix of )

CVE-2026-118781 · Severity: low · CVSS 3.1 · Published 2026-10-29

Forge (also called node-forge) is a native implementation of Transport Layer Security in JavaScript. Prior to 1.4.1, the affected implementation used BigInteger.prototype.modInverse(), bnModInverse(), lib/jsbn.js, RSA public exponent e to process the relevant input or security decision. node-forge's bundled jsbn implementation entered an infinite loop when BigInteger.prototype.modInverse() received a negative value or modulus. An attacker who could control the RSA public exponent passed to key generation, or a direct modInverse() operand, could block the Node.js event loop at full CPU. Parsed DER, PEM, JWK, PKCS#12, X.509, and TLS values are unsigned and cannot trigger this issue. This issue is fixed in version 1.4.1.

Technologies: node-forge (npm). Vendors: npm.

Quick answers

Is CVE-2026-118781 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-118781 being exploited in the wild.
How severe is CVE-2026-118781?
Low severity, with a CVSS score of 3.1, published 29 October 2026.
Which products and versions are affected?
node-forge (npm) <= 1.4.0, SEMVER:introduced=0,fixed=1.4.1.
Is there a fix for CVE-2026-118781?
Yes. node-forge (npm): upgrade to 1.4.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-118781?
Check whether you run node-forge (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • node-forge (npm): upgrade to 1.4.1 or later
    npm install node-forge@1.4.1

Affected products

  • node-forge (npm) <= 1.4.0, SEMVER:introduced=0,fixed=1.4.1

Identifiers

  • CVE-2026-118781
  • GHSA-h6cr-wjv9-3cpp

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.