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

Exp

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.

Published: 2026-03-27 Last update: 2026-04-08 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-33891 is rated Exploit Available (50.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.05%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-33891

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-33891

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-02 0.04% 0.05% +0.01%
2 2026-03-28 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33891

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-33891

GitHub Security Advisory for CVE-2026-33891

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

OS Trackers for CVE-2026-33891

vendor priority summary link
redhat high — https://access.redhat.com/security/cve/CVE-2026-33891
ubuntu medium CVE-2026-33891 medium priority: Ubuntu including 1 source packages (node-node-forge), 5 status rows across 5 suites (focal, jammy, noble, questing, upstream): needs-triage 3, DNE 2. https://ubuntu.com/security/CVE-2026-33891

Affected software / configurations for CVE-2026-33891

Vendor Product Version Raw CPE
digitalbazaar forge <= 1.3.3 cpe:2.3:a:digitalbazaar:forge:*:*:*:*:*:node.js:*:*

References for CVE-2026-33891

cvelogic Threat Intelligence