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Low, CVSS 3.7amended

Prototype pollution in jsii.configureCategories

GHSA-m56h-5xx3-2jc2

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (jsii 5.7.3, 5.6.4, 5.5.15, 5.4.46), 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

  • npm jsii

    Affected
    >= 5.7.0, < 5.7.3>= 5.6.0, < 5.6.4>= 5.5.0, < 5.5.15>= 5.4.0, < 5.4.46
    Fixed in
    5.7.3, 5.4.46, 5.5.15, 5.6.4

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Summary jsii is a TypeScript to JavaScript compiler that also extracts an interface definition manifest to generate RPC stubs in various programming languages. jsii is typically used as a command-line tool, but it can also be loaded as a library. When loaded as a library into a larger application, prototype pollution may happen if untrusted user input is passed to the library. When used as a command line-tool, this pollution cannot occur. Impact You may be impacted if you have written an application that loads jsii as a library, and passes untrusted user input into the jsii.configureCategories() function. In that case, a user can craft input in such a way that, following the invocation, a field named "category" with a user-controlled value is added to the JavaScript Object prototype. This will cause every object in the program (both new and existing) to have a field named "category", even if it shouldn't. This will not affect jsii itself, but it might affect the application you have…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-m56h-5xx3-2jc2

  2. Revision 1 · created ·

    Published from osv record GHSA-m56h-5xx3-2jc2

Agent brief

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

# Patch Next advisory brief: GHSA-m56h-5xx3-2jc2

Advisory: Prototype pollution in jsii.configureCategories
IDs: GHSA-m56h-5xx3-2jc2
Record: https://patchnext.com/advisories/ghsa-m56h-5xx3-2jc2 (revision 2, source checked 26 Oct 2026, 12:31 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: jsii 5.7.3, 5.6.4, 5.5.15, 5.4.46. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm jsii: affected >= 5.7.0, < 5.7.3; >= 5.6.0, < 5.6.4; >= 5.5.0, < 5.5.15; >= 5.4.0, < 5.4.46; fixed in 5.7.3, 5.4.46, 5.5.15, 5.6.4

## Suggested inspection (read-only)
- `npm ls jsii --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 jsii.
- 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://osv.dev/vulnerability/GHSA-m56h-5xx3-2jc2 (OSV record GHSA-m56h-5xx3-2jc2 lists affected ranges: npm jsii >=5.7.0 =5.6.0 =5.5.0 =5.4.0 <5.4.46 (fixed))
- Verified: https://github.com/advisories/GHSA-m56h-5xx3-2jc2 (GitHub-reviewed advisory GHSA-m56h-5xx3-2jc2 lists affected ranges: npm jsii >=5.7.0 =5.6.0 =5.5.0 =5.4.0 <5.4.46)

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