CVE-2026-4602: jsrsasign Negative Exponent Handling Leads To Vulnerability

HIGH
Advisory Identifier: GHSA-8qwj-4jxw-m8jw
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CVSS 7.5
CWE-681
Published
Advisory Summary

CVE-2026-4602 is a HIGH (CVSS 7.5) negative exponent handling leads to vulnerability (CWE-681: Incorrect Conversion between Numeric Types) affecting jsrsasign libraries in the npm ecosystem. The issue involves negative exponent handling leads to signature verification bypass. Remediation is available by upgrading affected packages to version 11.1.1.

CVE-2026-4602 at a Glance

CVE Identifier CVE-2026-4602
GHSA Identifier GHSA-8qwj-4jxw-m8jw
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-681: Incorrect Conversion between Numeric Types
Affected Product jsrsasign
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:H).

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 High (A:H)

How to Fix CVE-2026-4602

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

jsrsasign fixed: 11.1.1 
npm install jsrsasign@11.1.1
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 jsrsasign

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-4602, inspect your project dependencies using npm:

npm ls jsrsasign

Analyze the terminal output to locate any version of jsrsasign in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.1.1), your application is affected.

Note: The npm ls jsrsasign 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-681: Incorrect Conversion between Numeric Types, where when converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. if the resulting values are used in a sensitive context, then dangerous behaviors may occur. In jsrsasign, 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

Versions of the package jsrsasign before 11.1.1 are vulnerable to Incorrect Conversion between Numeric Types due to handling negative exponents in ext/jsbn2.js. An attacker can force the computation of incorrect modular inverses and break signature verification by calling modPow with a negative exponent.

CVE-2026-4602 Affected jsrsasign Versions

1 component(s)
Fixed Versions:
11.1.1
Product / Package Ecosystem Affected Versions Fixed Version
jsrsasign
npm/jsrsasign
npm
< 11.1.1
11.1.1

References

NVD — CVE-2026-4602 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4602
jsrsasign Source Repository REPOSITORY
https://github.com/kjur/jsrsasign/pull/650
Security Fix Commit FIX COMMIT
https://github.com/kjur/jsrsasign/commit/5ea1c32bb2aa894b4bd29849839afe4f98728195
jsrsasign Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371175
jsrsasign Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15812274
jsrsasign Security Information SECURITY
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4602.json
jsrsasign Source Repository REPOSITORY
https://github.com/kjur/jsrsasign
jsrsasign Source Repository REPOSITORY
https://gist.github.com/Kr0emer/7ecd2be7d17419e4677315ef3758faf5
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2450206
jsrsasign Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-4602
access.redhat.com/errata/rhsa-2026:69... WEB
https://access.redhat.com/errata/RHSA-2026:6926
access.redhat.com/errata/rhsa-2026:69... WEB
https://access.redhat.com/errata/RHSA-2026:6912
access.redhat.com/errata/rhsa-2026:67... WEB
https://access.redhat.com/errata/RHSA-2026:6720
access.redhat.com/errata/rhsa-2026:65... WEB
https://access.redhat.com/errata/RHSA-2026:6568
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19410
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19409
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19375

Frequently Asked Questions

What is CVE-2026-4602?
CVE-2026-4602 is a security vulnerability in jsrsasign involving Negative Exponent Handling Leads to Signature Verification Bypass under CWE-681: Incorrect Conversion between Numeric Types.
Which jsrsasign versions are affected?
Affected versions include releases prior to 11.1.1 across affected packages: jsrsasign.
What version fixes CVE-2026-4602?
Upgrading to 11.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is jsrsasign affected?
Yes, jsrsasign is affected in releases prior to 11.1.1. Upgrade your dependency to 11.1.1 or later.
What is the CVSS score of CVE-2026-4602?
CVE-2026-4602 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-4602?
CVE-2026-4602 is classified under CWE-681: Incorrect Conversion between Numeric Types (When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.).
How can I check npm dependencies for CVE-2026-4602?
Run the dependency tree command: 'npm ls jsrsasign'. 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-8qwj-4jxw-m8jw",
  "modified" : "2026-07-21T13:42:24Z",
  "published" : "2026-03-23T06:30:29Z",
  "aliases" : [ "CVE-2026-4602" ],
  "summary" : "jsrsasign: Negative Exponent Handling Leads to Signature Verification Bypass",
  "details" : "Versions of the package jsrsasign before 11.1.1 are vulnerable to Incorrect Conversion between Numeric Types due to handling negative exponents in ext/jsbn2.js. An attacker can force the computation of incorrect modular inverses and break signature verification by calling modPow with a negative exponent.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "jsrsasign"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "11.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-4602"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kjur/jsrsasign/pull/650"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kjur/jsrsasign/commit/5ea1c32bb2aa894b4bd29849839afe4f98728195"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371175"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15812274"
  }, {
    "type" : "WEB",
    "url" : "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4602.json"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/kjur/jsrsasign"
  }, {
    "type" : "WEB",
    "url" : "https://gist.github.com/Kr0emer/7ecd2be7d17419e4677315ef3758faf5"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2450206"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-4602"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:6926"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:6912"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:6720"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:6568"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19410"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19409"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19375"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-681" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-30T19:30:01Z",
    "nvd_published_at" : "2026-03-23T06:16:22Z"
  }
}