CVE-2026-107353

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

Published Oct 7, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Solution

Upgrade to traverse 0.6.12 or later, or, on older release lines, to 0.5.3, 0.4.7, or 0.3.10.


Vendor Workaround

Do not pass untrusted paths to set(). If that is not possible, require every path segment to be a string other than __proto__, constructor, or prototype, and confirm that each intermediate value along the path is an object before calling set().

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Ljharb
Ljharb traverse
Vendors & Products Ljharb
Ljharb traverse
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title traverse: set() can write to built-in prototypes via an untrusted path
Weaknesses CWE-1321
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
harborist
Published
Updated
Oct 7, 2026, 8:37 PM
Reserved
Oct 7, 2026, 7:20 PM
Status
Awaiting Analysis
Published
Oct 7, 2026, 8:17 PM
Modified
Oct 8, 2026, 9:34 PM