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

Medium · CVSS 5.3CVE-2026-63386

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

Answer in brief

CVE-2026-63386 records a Medium severity (CVSS 5.3) vulnerability in js-toml: Uncontrolled recursion in `load()` causes `RangeError` (stack exhaustion) on deeply nested input. The current sources do not mark it as known exploited. The current feed maps sunnyadn/js-toml (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 22, 2026Updated Sep 22, 2026Source checked Sep 22, 2026First seen by HOL Sep 22, 2026Material review Sep 22, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps sunnyadn/js-toml (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
sunnyadn/js-tomlgeneric	<1.1.3	1.1.3

Recommended response

Check inventory. Check lockfiles and deployed manifests for sunnyadn/js-toml.
Review the reported fix. Update sunnyadn/js-toml to 1.1.3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 22, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.