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Medium, CVSS 5.0amended

CyberChef: Prototype pollution in Series Chart operation

CVE-2026-57439GHSA-fx6f-382r-j72c

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (cyberchef 11.2.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.0 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS
  • CVE-2026-57439: 0.14% estimated exploitation activity in the next 30 days; percentile 2.97 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-fx6f-382r-j72c

  2. Revision 2 · amended ·

    Amended from osv record GHSA-fx6f-382r-j72c

  3. Revision 1 · created ·

    Published from ghsa record GHSA-fx6f-382r-j72c

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-57439

Advisory: CyberChef: Prototype pollution in Series Chart operation
IDs: CVE-2026-57439, GHSA-fx6f-382r-j72c
Record: https://patchnext.com/advisories/cve-2026-57439 (revision 3, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: cyberchef 11.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm cyberchef: affected < 11.2.0; fixed in 11.2.0

## Suggested inspection (read-only)
- `npm ls cyberchef --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on cyberchef.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fx6f-382r-j72c (GitHub-reviewed advisory GHSA-fx6f-382r-j72c lists affected ranges: npm cyberchef >=0 <11.2.0)
- Verified: https://osv.dev/vulnerability/GHSA-fx6f-382r-j72c (OSV record GHSA-fx6f-382r-j72c lists affected ranges: npm cyberchef >=0 <11.2.0 (fixed))

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