`scim-patch`, a library to perform SCIM patch, prior to version 0.9.1 performs prototype pollution when applying a SCIM PATCH operation whose `value` object contains a key like `"__proto__.someProp"`

Overview

scim-patch, a library to perform SCIM patch, prior to version 0.9.1 performs prototype pollution when applying a SCIM PATCH operation whose value object contains a key like "__proto__.someProp". After one such patch, Object.prototype.someProp is set process-wide, affecting every plain object in the Node process. Any service that calls scimPatch() on attacker-controlled JSON (i.e. any SCIM endpoint accepting PATCH from an external IdP) is exploitable on a stock Node runtime. Version 0.9.1 contains a patch. A workaround is available. Calling Object.freeze(Object.prototype) (and the same on Array.prototype, Function.prototype) at process startup neutralizes this class of bug — assignment to a frozen prototype becomes a silent no-op in sloppy mode or a TypeError in strict mode. Node's --frozen-intrinsics flag does this for built-ins automatically.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Package advisory (CVE-2026-48170)

Affected packages:

• scim-patch <= 0.9.0

Patched in:

• scim-patch 0.9.1

Source: https://github.com/advisories/GHSA-9m6g-wc8r-q59c