CVE-2026-63386
Received Received - Intake

Stack Overflow in js-toml TOML Parser

Vulnerability report for CVE-2026-63386, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-22

Last updated on: 2026-09-22

Assigner: GitHub, Inc.

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-22
Last Modified
2026-09-22
Generated
2026-09-22
AI Q&A
2026-09-22
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
sunnyadn js-toml to 1.1.3 (exc)
sunnyadn js-toml 1.1.3

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-674 The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

CVE-2026-63386 is a vulnerability in the js-toml library where deeply nested arrays, inline tables, or long dotted keys in TOML input can cause the parser to exceed the V8 call stack limit. This leads to a raw RangeError instead of the expected SyntaxParseError, potentially crashing the application or worker process and causing denial of service.

Detection Guidance

To detect this vulnerability, check if your system uses js-toml versions 1.1.2 or earlier. Run: npm list js-toml. If the version is below 1.1.3, the system is vulnerable. Monitor for crashes or RangeError exceptions during TOML parsing operations.

Impact Analysis

If you use js-toml to parse attacker-controlled TOML data, an attacker could craft deeply nested input to crash your application or worker process. This could disrupt service availability, even with small payloads. Applications handling only SyntaxParseError may crash due to unexpected RangeError exceptions.

Mitigation Strategies

Upgrade js-toml to version 1.1.3 or later using: npm update js-toml. If upgrading is not possible, implement a wrapper around the load() function to catch RangeError and convert it to SyntaxParseError. Set a maximum depth limit (e.g., 100) for parsing operations.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-63386. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart