CVE-2026-49293

Description

js-toml is a TOML parser for JavaScript, fully compliant with the TOML 1.0.0 Spec. Versions up to and including 1.1.0 parse hexadecimal / octal / binary integer literals via a hand-written `parseBigInt` loop that multiplies a `BigInt` accumulator by the radix once per input digit. Each iteration performs a `BigInt * BigInt` operation on an accumulator that grows linearly with the number of digits already consumed, so the whole loop is O(n²) in the literal length. The lexer regex places no upper bound on the literal length, so a single TOML document containing one ~500 kB hex literal pins one CPU core for ~40 seconds on a modern laptop (Apple M-series, Node v22). Memory amplification is bounded but CPU amplification is severe and grows quadratically: doubling the literal length quadruples the work. A caller that invokes `load()` on attacker-controlled TOML (configuration upload endpoints, CI/CD systems ingesting third-party `*.toml`, IDE plugins, build tools) is exposed to a single-request CPU exhaustion DoS. Version 1.1.1 fixes the issue.

CVSS 3.1 breakdown

Affected products

Remediation

References

• https://github.com/sunnyadn/js-toml/commit/1abcb31dc7b1fa88e4c848a8d108891cfbb96fa2Patch
• https://github.com/sunnyadn/js-toml/releases/tag/v1.1.1Release Notes
• https://github.com/sunnyadn/js-toml/security/advisories/GHSA-wp3c-266w-4qfqExploitMitigationVendor Advisory

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