CVE-2026-2739: Bn.js Bn.js Affected By An Infinite Vulnerability

MODERATE
Advisory Identifier: GHSA-378v-28hj-76wf
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CVSS 5.3
CWE-835
Published
Advisory Summary

CVE-2026-2739 is a MODERATE (CVSS 5.3) bn.js affected by an infinite vulnerability (CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')) affecting Bn.js libraries in the npm ecosystem. The issue involves bn.js affected by an infinite loop. Remediation is available by upgrading affected packages to version 4.12.3, 5.2.3.

CVE-2026-2739 at a Glance

CVE Identifier CVE-2026-2739
GHSA Identifier GHSA-378v-28hj-76wf
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Product Bn.js
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2026-2739

To remediate this vulnerability, upgrade all affected Bn.js dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

bn.js fixed: 4.12.3 
npm install bn.js@4.12.3
bn.js fixed: 5.2.3 
npm install bn.js@5.2.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls bn.js

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-2739, inspect your project dependencies using npm:

npm ls bn.js

Analyze the terminal output to locate any version of Bn.js in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.12.3), your application is affected.

Note: The npm ls bn.js command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'), where the product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. In Bn.js, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

This affects versions of the package bn.js before 4.12.3 and 5.2.3. 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.

CVE-2026-2739 Affected Bn.js Versions

2 component(s)
Fixed Versions:
4.12.35.2.3
Product / Package Ecosystem Affected Versions Fixed Version
bn.js
npm/bn.js
npm
< 4.12.3
4.12.3
bn.js
npm/bn.js
npm
≥ 5.0.0
< 5.2.3
5.2.3

References

NVD — CVE-2026-2739 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2739
Bn.js Source Repository REPOSITORY
https://github.com/indutny/bn.js/issues/186
Bn.js Source Repository REPOSITORY
https://github.com/indutny/bn.js/issues/316
Bn.js Source Repository REPOSITORY
https://github.com/indutny/bn.js/issues/316#issuecomment-3924217358
Bn.js Source Repository REPOSITORY
https://github.com/indutny/bn.js/pull/317
Security Fix Commit FIX COMMIT
https://github.com/indutny/bn.js/commit/33df26b5771e824f303a79ec6407409376baa64b
Bn.js Source Repository REPOSITORY
https://gist.github.com/Kr0emer/02370d18328c28b5dd7f9ac880d22a91
Bn.js Source Repository REPOSITORY
https://github.com/indutny/bn.js
Bn.js Release RELEASE
https://github.com/indutny/bn.js/releases/tag/v5.2.3
Bn.js Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JS-BNJS-15274301

Frequently Asked Questions

What is CVE-2026-2739?
CVE-2026-2739 is a security vulnerability in Bn.js involving bn.js affected by an infinite loop under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop').
Which Bn.js versions are affected?
Affected versions include releases prior to 4.12.3, 5.2.3 across affected packages: bn.js.
What version fixes CVE-2026-2739?
Upgrading to 4.12.3, 5.2.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is bn.js affected?
Yes, bn.js is affected in releases prior to 4.12.3, 5.2.3. Upgrade your dependency to 4.12.3, 5.2.3 or later.
What is the CVSS score of CVE-2026-2739?
CVE-2026-2739 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2026-2739?
CVE-2026-2739 is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') (The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.).
How can I check npm dependencies for CVE-2026-2739?
Run the dependency tree command: 'npm ls bn.js'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-378v-28hj-76wf",
  "modified" : "2026-02-24T14:45:53Z",
  "published" : "2026-02-20T06:30:39Z",
  "aliases" : [ "CVE-2026-2739" ],
  "summary" : "bn.js affected by an infinite loop",
  "details" : "This affects versions of the package bn.js before 4.12.3 and 5.2.3. 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "bn.js"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.12.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "bn.js"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0"
      }, {
        "fixed" : "5.2.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-2739"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/indutny/bn.js/issues/186"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/indutny/bn.js/issues/316"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/indutny/bn.js/issues/316#issuecomment-3924217358"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/indutny/bn.js/pull/317"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/indutny/bn.js/commit/33df26b5771e824f303a79ec6407409376baa64b"
  }, {
    "type" : "WEB",
    "url" : "https://gist.github.com/Kr0emer/02370d18328c28b5dd7f9ac880d22a91"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/indutny/bn.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/indutny/bn.js/releases/tag/v5.2.3"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JS-BNJS-15274301"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-20T21:18:31Z",
    "nvd_published_at" : "2026-02-20T05:17:53Z"
  }
}