What’s Vulnerable › Vulnerabilities

CVE-2026-33891: Forge has Denial of Service via Infinite Loop in BigInteger.modInverse() with Zero Input

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-27 · updated 2026-10-26
• Weakness: CWE-835

Description

Forge (also called `node-forge`) is a native implementation of Transport Layer Security in JavaScript. Prior to version 1.4.0, 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. Version 1.4.0 patches the issue.

Affected products

• digitalbazaar forge: through 1.3.3
• Npm Node-Forge: before 1.4.0 — fixed in 1.4.0

How to fix

Upgrade to a fixed version: Npm Node-Forge 1.4.0. Check the vendor advisory for mitigations.

References

• https://github.com/digitalbazaar/forge/commit/9bb8d67b99d17e4ebb5fd7596cd699e11f25d023
• https://github.com/digitalbazaar/forge/security/advisories/GHSA-5m6q-g25r-mvwx
• https://access.redhat.com/errata/RHSA-2026:13826
• https://access.redhat.com/errata/RHSA-2026:24761
• https://access.redhat.com/errata/RHSA-2026:24762
• https://access.redhat.com/errata/RHSA-2026:34342
• https://access.redhat.com/errata/RHSA-2026:9742
• https://access.redhat.com/security/cve/CVE-2026-33891
• https://bugzilla.redhat.com/show_bug.cgi?id=2452450
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33891.json

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