js-toml vulnerable to CPU exhaustion via O(n^2) BigInt construction on radix-prefixed integer literals

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-49293: 0.64% estimated exploitation activity in the next 30 days; percentile 50.92 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary `js-toml` 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. CWE-1333…

Published by the source

26 Jun 2026, 22:21 UTC

Last modified by the source

4 Nov 2026, 03:45 UTC

Source last checked

4 Nov 2026, 06:00 UTC

1. Revision 4 · amended · 4 Nov 2026

   Amended from osv record GHSA-wp3c-266w-4qfq

2. Revision 3 · amended · 4 Nov 2026

   Amended from ghsa record GHSA-wp3c-266w-4qfq

3. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-wp3c-266w-4qfq

4. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-wp3c-266w-4qfq

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# Patch Next advisory brief: CVE-2026-49293

Advisory: js-toml vulnerable to CPU exhaustion via O(n^2) BigInt construction on radix-prefixed integer literals
IDs: CVE-2026-49293, GHSA-wp3c-266w-4qfq
Record: https://patchnext.com/advisories/cve-2026-49293 (revision 4, source checked 4 Nov 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: js-toml 1.1.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm js-toml: affected < 1.1.2; fixed in 1.1.2

## Suggested inspection (read-only)
- `npm ls js-toml --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on js-toml.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-wp3c-266w-4qfq (OSV record GHSA-wp3c-266w-4qfq lists affected ranges: npm js-toml >=0 <1.1.1 (fixed))
- Verified: https://github.com/advisories/GHSA-wp3c-266w-4qfq (GitHub-reviewed advisory GHSA-wp3c-266w-4qfq lists affected ranges: npm js-toml >=0 <=1.1.0)
- Verified: https://github.com/advisories/GHSA-wp3c-266w-4qfq (GitHub-reviewed advisory GHSA-wp3c-266w-4qfq lists affected ranges: npm js-toml >=0 <=1.1.1)
- Verified: https://osv.dev/vulnerability/GHSA-wp3c-266w-4qfq (OSV record GHSA-wp3c-266w-4qfq lists affected ranges: npm js-toml >=0 <1.1.2 (fixed))

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