Bug 2528256 (CVE-2026-63376)

Summary: CVE-2026-63376 toml-node: toml-node: Arbitrary Code Execution via Prototype Pollution in TOML Parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in toml-node, a software library used for parsing TOML (Tom's Obvious, Minimal Language) files in Node.js and web applications. A remote attacker could exploit a vulnerability known as prototype pollution by providing specially crafted TOML input. This could allow the attacker to inject properties into fundamental JavaScript objects, potentially leading to arbitrary code execution, denial of service, or bypassing security controls within the affected application.
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Description OSIDB Bzimport 2026-09-03 20:41:26 UTC 
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.