CVE-2026-93749: Source map js Remote Code Execution Vulnerability

HIGH
Advisory Identifier: GHSA-68fv-2mgg-jv7q
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CVSS 7.5
CWE-1284
Published
Advisory Summary

CVE-2026-93749 is a HIGH (CVSS 7.5) remote code execution vulnerability (CWE-1284: Improper Validation of Specified Quantity in Input) affecting Source map js libraries in the npm ecosystem. The issue involves source-map-js allows event-loop denial of service through indexed source-map section offsets. Remediation is available by upgrading affected packages to version 1.2.2.

CVE-2026-93749 at a Glance

CVE Identifier CVE-2026-93749
GHSA Identifier GHSA-68fv-2mgg-jv7q
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-1284: Improper Validation of Specified Quantity in Input
Affected Product Source map js
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-2026-93749

To remediate this vulnerability, upgrade all affected Source map 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.

source-map-js fixed: 1.2.2 
npm install source-map-js@1.2.2
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 source-map-js

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-93749, inspect your project dependencies using npm:

npm ls source-map-js

Analyze the terminal output to locate any version of Source map js in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.2.2), your application is affected.

Note: The npm ls source-map-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-1284: Improper Validation of Specified Quantity in Input, where the product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties. In Source map 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

source-map-js through 1.2.1 fails to validate the per-section offset line value in indexed source maps, allowing attackers to specify arbitrary numeric values. Attackers can supply extremely large offset line values that cause synchronous event loop blocking for extended periods, preventing the service from handling other requests.

CVE-2026-93749 Affected Source map js Versions

1 component(s)
Fixed Versions:
1.2.2
Product / Package Ecosystem Affected Versions Fixed Version
source-map-js
npm/source-map-js
npm
≥ 1.0.0
< 1.2.2
1.2.2

References

NVD — CVE-2026-93749 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-93749
Source map js Source Repository REPOSITORY
https://github.com/7rulnik/source-map-js/issues/76
Source map js Source Repository REPOSITORY
https://github.com/7rulnik/source-map-js/pull/79
Security Fix Commit FIX COMMIT
https://github.com/7rulnik/source-map-js/commit/cf7658058ceeaa8619d5ae0ec90be6905209d016
Source map js Source Repository REPOSITORY
https://github.com/7rulnik/source-map-js
Source map js Source Repository REPOSITORY
https://github.com/7rulnik/source-map-js/blob/c1cd8904bb7bd0c7fb5879fcda48134d82a27934/lib/source-node.js#L115-L118
Source map js Release RELEASE
https://github.com/7rulnik/source-map-js/releases/tag/v1.2.2
www.vulncheck.com/advisories/source-m... WEB
https://www.vulncheck.com/advisories/source-map-js-through-1.2.1-event-loop-denial-of-service

Frequently Asked Questions

What is CVE-2026-93749?
CVE-2026-93749 is a security vulnerability in Source map js involving source-map-js allows event-loop denial of service through indexed source-map section offsets under CWE-1284: Improper Validation of Specified Quantity in Input.
Which Source map js versions are affected?
Affected versions include releases prior to 1.2.2 across affected packages: source-map-js.
What version fixes CVE-2026-93749?
Upgrading to 1.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is source-map-js affected?
Yes, source-map-js is affected in releases prior to 1.2.2. Upgrade your dependency to 1.2.2 or later.
What is the CVSS score of CVE-2026-93749?
CVE-2026-93749 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-2026-93749?
CVE-2026-93749 is classified under CWE-1284: Improper Validation of Specified Quantity in Input (The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.).
How can I check npm dependencies for CVE-2026-93749?
Run the dependency tree command: 'npm ls source-map-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-68fv-2mgg-jv7q",
  "modified" : "2026-10-05T23:31:22Z",
  "published" : "2026-09-18T18:31:44Z",
  "aliases" : [ "CVE-2026-93749" ],
  "summary" : "source-map-js allows event-loop denial of service through indexed source-map section offsets",
  "details" : "source-map-js through 1.2.1 fails to validate the per-section offset line value in indexed source maps, allowing attackers to specify arbitrary numeric values. Attackers can supply extremely large offset line values that cause synchronous event loop blocking for extended periods, preventing the service from handling other requests.",
  "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "source-map-js"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0"
      }, {
        "fixed" : "1.2.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-93749"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/7rulnik/source-map-js/issues/76"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/7rulnik/source-map-js/pull/79"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/7rulnik/source-map-js/commit/cf7658058ceeaa8619d5ae0ec90be6905209d016"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/7rulnik/source-map-js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/7rulnik/source-map-js/blob/c1cd8904bb7bd0c7fb5879fcda48134d82a27934/lib/source-node.js#L115-L118"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/7rulnik/source-map-js/releases/tag/v1.2.2"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/source-map-js-through-1.2.1-event-loop-denial-of-service"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1284" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-05T23:31:22Z",
    "nvd_published_at" : "2026-09-18T18:18:33Z"
  }
}