Prototype Pollution in Binarymuse Toml-Node
CVE-2026-63376
toml-node is a TOML parser for Node.js and the browser. Prior to 4.1.2, toml.parse() in lib/compiler.js can be tricked by a table path such as a.b.y.__proto__.__proto__, allowing traversal from a scalar value into Number.prototype and Object.prototype. The currentPath tracking value uses both arrays and strings, so valueAssignments records a comma-joined path such as a,b.y while deepRef checks the dot-joined path a.b.y, allowing the duplicate-key guard to miss and attacker-controlled keys to be written to Object.prototype. A table-array prefix-clearing path in addTableArray can also erase guard state before the same __proto__ traversal. Injected properties become visible throughout the Node.js process and can cause denial of service, logic or authorization bypass, or code execution when an application contains a suitable gadget. This issue is fixed in version 4.1.2.
Vulnerability class: Prototype Pollution
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L.
EPSS exploit prediction
EPSS: 0.007 (51.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.007 · change: +0.003
Affected products
- Binarymuse Toml-Node — versions < 4.1.2
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-63376?
- CVE-2026-63376 is a high-severity vulnerability in Binarymuse Toml-Node, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 8.2/10. Published 2026-09-03.
- How severe is CVE-2026-63376?
- High severity. CVSS v3 base score is 8.2 out of 10.