CVE-2026-107353traverse: set() can write to built-in prototypes via an untrusted path

traverse (npm) versions 0.3.6 through 0.3.9, 0.4.0 through 0.4.6, 0.5.0 through 0.5.2, and 0.6.0 through 0.6.11 allow prototype pollution through set(). When the path passed to set() crosses a primitive value, the next path segment is resolved on that primitive's built-in prototype, so an application that passes an untrusted path to set() lets an attacker add or overwrite properties of String.prototype, Number.prototype, or Boolean.prototype using plain JSON data, for example traverse({ name: 'bob' }).set(['name', '__proto__', 'polluted'], 'yes'). Object.prototype was reachable only with a non-data path segment, such as an object whose toString returns a different value on each call, or through a Proxy that accepts an assignment without storing it. This is fixed in 0.3.10, 0.4.7, 0.5.3, and 0.6.12.

CVSS

6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Weakness (CWE)

CWE-1321

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

harborist

NVD analysis

Awaiting Analysis

Record last updated

Oct 7, 2026

First seen by InfoSec Signals

Oct 9, 2026

The CVE record on cve.org · NVD's entry

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