CVE-2026-49356: @babel/core Remote Code Execution Vulnerability

LOW
Advisory Identifier: GHSA-4x5r-pxfx-6jf8
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CVSS 3.2
CWE-200 CWE-22
Published
Advisory Summary

CVE-2026-49356 is a LOW (CVSS 3.2) remote code execution vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting @babel/core libraries in the npm ecosystem. The issue involves arbitrary file read via sourcemappingurl comment. Remediation is available by upgrading affected packages to version 8.0.0-rc.6, 7.29.6.

CVE-2026-49356 at a Glance

CVE Identifier CVE-2026-49356
GHSA Identifier GHSA-4x5r-pxfx-6jf8
Severity LOW
CVSS v3.1 Base Score 3.2
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product @babel/core
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 3.2

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

Attack Vector Local (AV:L)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-49356

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

@babel/core fixed: 8.0.0-rc.6 
npm install @babel/core@8.0.0-rc.6
@babel/core fixed: 7.29.6 
npm install @babel/core@7.29.6
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 @babel/core

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-49356, inspect your project dependencies using npm:

npm ls @babel/core

Analyze the terminal output to locate any version of @babel/core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 8.0.0-rc.6), your application is affected.

Note: The npm ls @babel/core 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-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In @babel/core, 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

## Impact Using `@babel/core` to compile maliciously crafted code can allow ab attacker to read any source map from the system that is running Babel, if these conditions are _all_ true: - the attacker controls the input source code - the attacker can read the output source code - the attacker knows the path of the source map file that they want to read **Users that only compile trusted code are not impacted.** ## Patches The vulnerability has been fixed in `@babel/core@7.29.6` and `@babel/core@8.0.0-rc.6`. ## Workarounds Callers can mitigate the issue without upgrading by setting [`inputSourceMap: false`](https://babeljs.io/docs/options#inputsourcemap) in their Babel options. Callers can also manually extract the `#sourceMappingURL` comment from the input source code, validate whether the source map that it links to is allowed to be read, and if it is pass an object to `inputSourceMap` (passing `false` when it's not). ## Credits Thanks Teodor-Cristian Radoi for reporting the vulnerability.

CVE-2026-49356 Affected @babel/core Versions

2 component(s)
Fixed Versions:
8.0.0-rc.67.29.6
Product / Package Ecosystem Affected Versions Fixed Version
@babel/core
npm/@babel/core
npm
≥ 8.0.0-alpha.0
< 8.0.0-rc.6
8.0.0-rc.6
@babel/core
npm/@babel/core
npm
< 7.29.6
7.29.6

References

GitHub Advisory / Wiki ADVISORY
https://github.com/babel/babel/security/advisories/GHSA-4x5r-pxfx-6jf8
NVD — CVE-2026-49356 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49356
babeljs.io/docs/options WEB
https://babeljs.io/docs/options#inputsourcemap
@babel/core Source Repository REPOSITORY
https://github.com/babel/babel

Frequently Asked Questions

What is CVE-2026-49356?
CVE-2026-49356 is a security vulnerability in @babel/core involving Arbitrary File Read via sourceMappingURL Comment under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which @babel/core versions are affected?
Affected versions include releases prior to 8.0.0-rc.6, 7.29.6 across affected packages: @babel/core.
What version fixes CVE-2026-49356?
Upgrading to 8.0.0-rc.6, 7.29.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @babel/core affected?
Yes, @babel/core is affected in releases prior to 8.0.0-rc.6, 7.29.6. Upgrade your dependency to 8.0.0-rc.6, 7.29.6 or later.
What is the CVSS score of CVE-2026-49356?
CVE-2026-49356 has a CVSS v3.1 base score of 3.2 (LOW) with vector string CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N.
What CWE is associated with CVE-2026-49356?
CVE-2026-49356 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check npm dependencies for CVE-2026-49356?
Run the dependency tree command: 'npm ls @babel/core'. 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-4x5r-pxfx-6jf8",
  "modified" : "2026-07-15T22:05:27Z",
  "published" : "2026-06-15T17:14:14Z",
  "aliases" : [ "CVE-2026-49356" ],
  "summary" : "@babel/core: Arbitrary File Read via sourceMappingURL Comment",
  "details" : "## Impact\n\nUsing `@babel/core` to compile maliciously crafted code can allow ab attacker to read any source map from the system that is running Babel, if these conditions are _all_ true:\n- the attacker controls the input source code\n- the attacker can read the output source code\n- the attacker knows the path of the source map file that they want to read\n\n**Users that only compile trusted code are not impacted.**\n\n## Patches\n\nThe vulnerability has been fixed in `@babel/core@7.29.6` and `@babel/core@8.0.0-rc.6`.\n\n## Workarounds\n\nCallers can mitigate the issue without upgrading by setting [`inputSourceMap: false`](https://babeljs.io/docs/options#inputsourcemap) in their Babel options.\n\nCallers can also manually extract the `#sourceMappingURL` comment from the input source code, validate whether the source map that it links to is allowed to be read, and if it is pass an object to `inputSourceMap` (passing `false` when it's not).\n\n## Credits\n\nThanks Teodor-Cristian Radoi for reporting the vulnerability.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@babel/core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0-alpha.0"
      }, {
        "fixed" : "8.0.0-rc.6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "< 8.0.0-rc.5"
    }
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@babel/core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.29.6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 7.29.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/babel/babel/security/advisories/GHSA-4x5r-pxfx-6jf8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-49356"
  }, {
    "type" : "WEB",
    "url" : "https://babeljs.io/docs/options#inputsourcemap"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/babel/babel"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-22" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-15T17:14:14Z",
    "nvd_published_at" : "2026-06-22T18:16:41Z"
  }
}