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Vulnerability · Published Sep 22, 2026 · Assigned by GitHub_M

CVE-2026-63386js-toml: Uncontrolled recursion in `load()` causes `RangeError` (stack exhaustion) on deeply nested input

Medium 5.3

In plain English

A medium-severity security flaw in js-toml from sunnyadn. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).

Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.4%top 69.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

js-toml is a TOML parser for JavaScript. Prior to 1.1.3, load() does not bound nesting or dotted-key depth in the recursive parser at src/load/parser.ts or the interpreter at src/load/interpreter.ts, so deeply nested arrays, deeply nested inline tables, or long dotted keys can exhaust the V8 call stack and throw a raw RangeError instead of the documented SyntaxParseError. Applications that parse attacker-controlled TOML and handle only SyntaxParseError can rethrow the unexpected exception, which can terminate a worker or process and cause denial of service. The exception is synchronous and catchable by consumers that handle all exceptions, and the issue does not affect confidentiality or integrity. This issue is fixed in version 1.1.3.

Affected products (as reported)

VendorProductVersions
sunnyadn js-toml < 1.1.3

Weakness: CWE-674 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References