HighCVE-2026-33891

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

Published 27.03.2026Last modified 26.10.2026Sources: Red Hat, CVE.org, Msrc Update Guide, OSV, BSI

Public exploit

What is affected, what to do

An exploit is publicly available. Update Digitalbazaar Forge to version 1.4.0.

Affected: Digitalbazaar Forge lt *..1.4.0
Fixed in: Digitalbazaar Forge 1.4.0

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

7.5

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

7.5

CVSS v3

Severity High on the scale from 0 to 10.

Source: Red Hat, CVE.org, Msrc Update Guide, OSV, BSI

0.6 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 48.9

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 72.22 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: PoC (publicly reported)
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 7.5 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.5
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.6 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 48.9; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 27.03.2026
CISA assessment (SSVC): Exploitation: proof of concept · automatable · Technical impact: partial; Source: CISA Vulnrichment, as of 30 March 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-835, CWE-606

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

A flaw was found in the node-forge library, a JavaScript implementation of Transport Layer Security. This vulnerability, inherited from the bundled jsbn library, allows a remote attacker to cause a Denial of Service (DoS). When the BigInteger.modInverse() function is called with a zero value, it enters an infinite loop, causing the process to hang indefinitely and consume 100% of the CPU resources.

Source: redhat_csaf, NVD (NIST), Microsoft Security Update Guide, CVE.org (MITRE), OSV (Open Source Vulnerabilities), cvelistv5, BSI WID Portal, BSI CSAF

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
digitalbazaar	forge	`< 1.4.0` `≤ 1.3.3`	`1.4.0` —
npm	node-forge	`—`	—

Vendors and products

Digitalbazaar Forge

Weakness classes (CWE)

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
Base
The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
Entry at MITRE CWE-835
CWE-606Unchecked Input for Loop Condition
Base
The product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping.
Entry at MITRE CWE-606

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

Reference tagged as exploit	github.com (opens in a new tab)	PoC (publicly reported)reported, not verified	—

References & sources

github.comdigitalbazaar/forge/security/advisories/GHSA-5m6q-g25r-mvwxweb, x_refsource_CONFIRM, Exploit, Vendor advisory
NVD (NIST)vuln/detail/CVE-2026-33891advisory
github.comdigitalbazaar/forge/commit/9bb8d67b99d17e4ebb5fd7596cd699e11f25…web, x_refsource_MISC, Patch
github.comdigitalbazaar/forgepackage
access.redhat.comsecurity/cve/CVE-2026-33891Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2452450Issue tracking, x_refsource_REDHAT
security.access.redhat.comdata/csaf/v2/vex/2026/cve-2026-33891.jsonx_sadp-csaf-vex
access.redhat.comerrata/RHSA-2026:24761Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:24762Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:34342Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:9742Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:13826Vendor advisory, x_refsource_REDHAT

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

31.08.2026Record modifiedGitHub

New references:

Show 6 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/digitalbazaar/forge/commit/9bb8d67b99d17e4ebb5fd7596cd699e11f25d023
Reference	added	—	https://github.com/digitalbazaar/forge/security/advisories/GHSA-5m6q-g25r-mvwx
Reference	removed	https://github.com/digitalbazaar/forge/commit/9bb8d67b99d17e4ebb5fd7596cd699e11f25d023	—
Reference	removed	https://github.com/digitalbazaar/forge/security/advisories/GHSA-5m6q-g25r-mvwx	—
Reference type	removed	https://github.com/digitalbazaar/forge/commit/9bb8d67b99d17e4ebb5fd7596cd699e11f25d023 Types: Patch	—
Reference type	removed	https://github.com/digitalbazaar/forge/security/advisories/GHSA-5m6q-g25r-mvwx Types: Exploit, Vendor Advisory	—

Source identifier: security-advisories@github.com

31.08.2026Record modifiedRed Hat ADP

New references:

and 4 more references

Show 17 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/33xxx/CVE-2026-33891.json">CVE-2026-33891</a>
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:13826
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:24761
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:24762
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:34342
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:9742
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-33891
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2452450
Reference	added	—	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33891.json
Reference	removed	https://access.redhat.com/errata/RHSA-2026:13826	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:24761	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:24762	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:34342	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:9742	—
Reference	removed	https://access.redhat.com/security/cve/CVE-2026-33891	—
Reference	removed	https://bugzilla.redhat.com/show_bug.cgi?id=2452450	—
Reference	removed	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33891.json	—

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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