Vulnerability · Published Sep 3, 2026 · Assigned by GitHub_M
CVE-2026-63376toml-node: Prototype Pollution Leads to `Object.prototype` Corruption via `__proto__` Key-Path Desynchronization
High 8.2
In plain English
A high-severity prototype pollution in toml-node from BinaryMuse. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | toml | 4.1.2 | GHSA-v5mp-jgw5-2x6j |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| BinaryMuse | toml-node | < 4.1.2 |
Weakness: CWE-1321 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
References
- https://github.com/BinaryMuse/toml-node/security/advisories/GHSA-v5mp-jgw5-2x6j x_refsource_CONFIRM
- https://github.com/BinaryMuse/toml-node/commit/def6ab5ea99038c0dd482cd6af1745a6af8b4c44 x_refsource_MISC
- https://github.com/BinaryMuse/toml-node/commit/dfaff662276adc38a2e03df3139f7119b0185463 x_refsource_MISC