Vulnerabilities in pkg:npm/cyberchef

PACKAGE
Advisory Identifier: GHSA-fx6f-382r-j72c
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Advisory Summary

CVE-2026-57439 is a MODERATE (CVSS 5.0) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting CyberChef libraries in the npm ecosystem. The issue involves prototype pollution in series chart operation. Remediation is available by upgrading affected packages to version 11.2.0.

3 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/cyberchef

3 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/cyberchef. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-fx6f-382r-j72c CVE-2026-57439 MODERATE CyberChef: Prototype pollution in Series Chart operation
GHSA-h4hv-92pp-pcjg CVE-2026-42615 HIGH CyberChef has a Cross-site Scripting issue
GHSA-jp6r-xcjj-5h7r CVE-2019-15532 MODERATE Cross-Site Scripting in cyberchef

CVE-2026-57439 at a Glance

CVE Identifier CVE-2026-57439
GHSA Identifier GHSA-fx6f-382r-j72c
Severity MODERATE
CVSS v3.1 Base Score 5.0
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product CyberChef
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.0

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

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

How to Fix CVE-2026-57439

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

cyberchef fixed: 11.2.0 
npm install cyberchef@11.2.0
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 cyberchef

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-57439, inspect your project dependencies using npm:

npm ls cyberchef

Analyze the terminal output to locate any version of CyberChef in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.2.0), your application is affected.

Note: The npm ls cyberchef 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-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In CyberChef, 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

On 5 June 2026 CyberChef received a security vulnerability report from @hyuunnn detailing a vulnerability in the Series Chart operation, where malicious input could result in prototype pollution of the data structures outputted from the operation. Other operations following Series Chart could have their behaviour manipulated by the attacker-controlled prototype, for example, injecting malicious content into their HTML output. In this case, a demonstration was provided that chained the Series Chart operation with the Parse UDP operation to cause attacker controlled JavaScript to be executed. ## Details When the Series Chart operation parses user-supplied CSV, it accepts `__proto__` as a key and uses it to pollute the object. The objToTbale function in src/core/lib/Protocol.mjs, used in a number of IP parsing operations, renders data items within `<td>` tags without escaping. These bugs can be chained to produce an XSS vulnerability. **Proof of Concept** [https://gchq.github.io/CyberChef/#recipe=Series_chart('CRLF','Comma','',1,'')Parse_UDP('Raw')&input=X19wcm90b19fLDxpbWcgc3JjPXggb25lcnJvcj1hbGVydChkb2N1bWVudC5kb21haW4pPiwx](https://gchq.github.io/CyberChef/#recipe=Series_chart('CRLF','Comma','',1,'')Parse_UDP('Raw')&input=X19wcm90b19fLDxpbWcgc3JjPXggb25lcnJvcj1hbGVydChkb2N1bWVudC5kb21haW4pPiwx) Encoded input data is: ``` __proto__,<img src=x onerror=alert(document.domain)>,1 ``` ### Impact Objects with attacker controlled prototypes could be processed by CyberChef operations. This enabled control of the output of some operations, and in particular, the ability to insert malicious JavaScript into the output of the Parse UDP operation. ### Patches This has been patched in release v11.2.0. ### Workarounds No workarounds are available. Users must upgrade to CyberChef v11.2.0.

CVE-2026-57439 Affected CyberChef Versions

1 component(s)
Fixed Versions:
11.2.0
Product / Package Ecosystem Affected Versions Fixed Version
cyberchef
npm/cyberchef
npm
< 11.2.0
11.2.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/gchq/CyberChef/security/advisories/GHSA-fx6f-382r-j72c
NVD — CVE-2026-57439 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-57439
CyberChef Source Repository REPOSITORY
https://github.com/gchq/CyberChef/issues/2568
CyberChef Source Repository REPOSITORY
https://github.com/gchq/CyberChef/pull/2569
Security Fix Commit FIX COMMIT
https://github.com/gchq/CyberChef/commit/85db3be5d0096859b810f0e8d3e151d5dc9b948f
CyberChef Source Repository REPOSITORY
https://github.com/gchq/CyberChef
CyberChef Release RELEASE
https://github.com/gchq/CyberChef/releases/tag/v11.2.0

Frequently Asked Questions

What is CVE-2026-57439?
CVE-2026-57439 is a security vulnerability in CyberChef involving Prototype pollution in Series Chart operation under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which CyberChef versions are affected?
Affected versions include releases prior to 11.2.0 across affected packages: cyberchef.
What version fixes CVE-2026-57439?
Upgrading to 11.2.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is cyberchef affected?
Yes, cyberchef is affected in releases prior to 11.2.0. Upgrade your dependency to 11.2.0 or later.
What is the CVSS score of CVE-2026-57439?
CVE-2026-57439 has a CVSS v3.1 base score of 5.0 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2026-57439?
CVE-2026-57439 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-57439?
Run the dependency tree command: 'npm ls cyberchef'. 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-fx6f-382r-j72c",
  "modified" : "2026-09-24T19:24:30Z",
  "published" : "2026-09-24T19:24:30Z",
  "aliases" : [ "CVE-2026-57439" ],
  "summary" : "CyberChef: Prototype pollution in Series Chart operation",
  "details" : "On 5 June 2026 CyberChef received a security vulnerability report from @hyuunnn detailing a vulnerability in the Series Chart operation, where malicious input could result in prototype pollution of the data structures outputted from the operation.\nOther operations following Series Chart could have their behaviour manipulated by the attacker-controlled prototype, for example, injecting malicious content into their HTML output.\n\nIn this case, a demonstration was provided that chained the Series Chart operation with the Parse UDP operation to cause attacker controlled JavaScript to be executed.\n\n## Details\nWhen the Series Chart operation parses user-supplied CSV, it accepts `__proto__` as a key and uses it to pollute the object.\nThe objToTbale function in src/core/lib/Protocol.mjs, used in a number of IP parsing operations, renders data items within `<td>` tags without escaping.\nThese bugs can be chained to produce an XSS vulnerability.\n\n**Proof of Concept**\n[https://gchq.github.io/CyberChef/#recipe=Series_chart('CRLF','Comma','',1,'')Parse_UDP('Raw')&input=X19wcm90b19fLDxpbWcgc3JjPXggb25lcnJvcj1hbGVydChkb2N1bWVudC5kb21haW4pPiwx](https://gchq.github.io/CyberChef/#recipe=Series_chart('CRLF','Comma','',1,'')Parse_UDP('Raw')&input=X19wcm90b19fLDxpbWcgc3JjPXggb25lcnJvcj1hbGVydChkb2N1bWVudC5kb21haW4pPiwx)\n\nEncoded input data is:\n```\n__proto__,<img src=x onerror=alert(document.domain)>,1\n```\n\n### Impact\nObjects with attacker controlled prototypes could be processed by CyberChef operations. This enabled control of the output of some operations, and in particular, the ability to insert malicious JavaScript into the output of the Parse UDP operation.\n\n### Patches\nThis has been patched in release v11.2.0.\n\n### Workarounds\nNo workarounds are available. Users must upgrade to CyberChef v11.2.0.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "cyberchef"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "11.2.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/gchq/CyberChef/security/advisories/GHSA-fx6f-382r-j72c"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-57439"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gchq/CyberChef/issues/2568"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gchq/CyberChef/pull/2569"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gchq/CyberChef/commit/85db3be5d0096859b810f0e8d3e151d5dc9b948f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gchq/CyberChef"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gchq/CyberChef/releases/tag/v11.2.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-24T19:24:30Z",
    "nvd_published_at" : "2026-07-08T16:16:31Z"
  }
}