CVE-2026-114144 in toml-node
Summary
by MITRE • 10/21/2026
toml-node is a TOML parser for Node.js and the browser. Prior to 5.0.1, toml.parse() passes unbounded hexadecimal, octal, binary, and decimal digit sequences from lib/parser.js to BigInt() before reduceInteger() in lib/compiler.js checks whether the resulting value fits the TOML 64-bit integer range. Converting a sufficiently long integer string consumes super-linear CPU time and synchronously blocks the Node.js event loop, allowing one attacker-supplied TOML document to deny service to concurrent work in the process. The later range check cannot prevent the conversion cost because it executes after BigInt(). This issue is fixed in version 5.0.1.
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Analysis
by VulDB Data Team • 10/21/2026
The vulnerability identified in toml-node versions prior to 5.0.1 represents a critical resource exhaustion flaw rooted in the order of operations within the parsing logic. The core technical defect lies in the sequence where unbounded numeric strings are converted into BigInt objects before any range validation occurs. Specifically, when the parser encounters hexadecimal, octal, binary, or decimal digit sequences, it immediately invokes the native BigInt() constructor to parse these values. This conversion process is computationally expensive and exhibits super-linear time complexity relative to the length of the input string. Consequently, an attacker can craft a TOML document containing extremely long numeric literals that force the JavaScript engine to perform excessive arithmetic operations during parsing.
This synchronous execution model poses a severe risk to Node.js applications because it blocks the event loop. In asynchronous environments like Node.js, blocking the main thread prevents the processing of other incoming requests and background tasks. By submitting a maliciously crafted TOML payload with oversized integer representations, an attacker can induce a Denial of Service condition that affects not only the specific request but also all concurrent work being handled by the same process instance. The subsequent range check performed in lib/compiler.js is rendered ineffective because it executes after the costly BigInt conversion has already consumed significant CPU resources and blocked execution for potentially extended periods.
From a classification perspective, this vulnerability aligns with CWE-400, which describes uncontrolled resource consumption leading to denial of service conditions. It also relates to CWE-787, as out-of-bounds writes are not the primary issue here; rather, it is an algorithmic complexity flaw where input validation fails to occur prior to expensive operations. In terms of attack patterns, this behavior mirrors aspects of ATT&CK technique T1496, Resource Hijacking, specifically through computational exhaustion that degrades system availability for legitimate users. The lack of pre-validation on the length or format of numeric inputs allows external actors to manipulate resource allocation in a way that is difficult to mitigate without code changes.
To address this vulnerability, organizations must upgrade to version 5.0.1 or later of toml-node, where the parsing logic has been corrected to validate integer ranges and lengths before attempting BigInt conversion. For applications unable to update immediately, implementing input validation at the application layer can provide a temporary mitigation strategy by rejecting TOML documents with excessively long numeric fields before they reach the parser. Additionally, deploying rate limiting or request size restrictions on endpoints that accept TOML payloads can help reduce the exposure window and limit the impact of potential exploitation attempts until a permanent fix is deployed.