CVE-2026-114143 in toml-node
Summary
by MITRE • 10/23/2026
toml-node is a TOML parser for Node.js and the browser. Prior to 5.0.1, toml.parse() repeatedly slices and rejoins every path prefix in lib/compiler.js while processing long dotted keys, table headers, array-of-tables headers, and inline-table keys in assign(), deepRef(), and setNestedKey(). The resulting quadratic work can block the Node.js event loop for several seconds, and sufficiently long paths can terminate the process through memory exhaustion. The maxDepth option does not limit key-segment count and therefore does not mitigate this path. This issue is fixed in version 5.0.1.
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Analysis
by VulDB Data Team • 10/23/2026
The vulnerability identified within toml-node versions prior to 5.0.1 represents a significant performance degradation and potential denial of service risk stemming from inefficient string manipulation algorithms during the parsing process. As a widely used TOML parser for Node.js environments, this library is susceptible to algorithmic complexity attacks where maliciously crafted input can trigger disproportionate resource consumption. The core technical flaw resides in the implementation of functions such as assign(), deepRef(), and setNestedKey() within lib/compiler.js. When processing long dotted keys, table headers, array-of-tables headers, or inline-table keys, these functions repeatedly slice and rejoin every path prefix associated with the input data structure. This approach results in quadratic time complexity relative to the length of the key paths, meaning that as the depth or number of segments increases, the computational effort required grows exponentially rather than linearly.
This inefficient handling of string operations directly impacts the operational stability of Node.js applications relying on this parser. Because Node.js operates on a single-threaded event loop model, any operation that blocks for an extended period prevents the application from processing other incoming requests or events. In the context of this vulnerability, sufficiently long and deeply nested TOML structures can cause the parsing process to block the event loop for several seconds, effectively rendering the service unresponsive during that window. This behavior aligns with CWE-400, which describes Uncontrolled Resource Consumption, as the application consumes excessive CPU cycles due to poor algorithmic efficiency rather than legitimate workload requirements.
Beyond simple performance degradation, the vulnerability poses a severe risk of process termination through memory exhaustion. The repeated creation and disposal of string slices during the parsing of deeply nested structures can lead to rapid heap growth if not managed efficiently by the garbage collector under high load conditions. This aligns with CWE-787, Out-of-bounds Write, in terms of resource impact, although technically it is more accurately categorized as a memory exhaustion vector due to inefficient allocation patterns rather than buffer overflows. Attackers can exploit this by submitting TOML payloads with extremely long or deeply nested key paths, forcing the parser into an infinite loop-like state that consumes all available system resources until the process crashes.
The mitigation strategy provided in version 5.0.1 addresses these issues by optimizing the internal handling of path prefixes and reducing the frequency of string concatenation operations. It is critical for developers to note that the existing maxDepth configuration option does not limit the count of key segments, meaning it offers no protection against this specific vector. Therefore, upgrading to version 5.0.1 or later is mandatory for any application processing untrusted TOML input. From a defensive perspective, organizations should also implement strict limits on input size and depth at the network layer before data reaches the parser, adhering to principles outlined in OWASP guidelines regarding Denial of Service prevention. This layered approach ensures that even if parsing logic changes, external controls remain in place to protect against resource exhaustion attacks targeting other components within the application stack.