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Response snapshot Oct 27, 2026, 01:11 UTC

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VulnerabilityCVE-2026-114143

toml-node: Quadratic-complexity DoS via long dotted keys or table paths in toml.parse()

`toml.parse()` is vulnerable to a quadratic-complexity (O(n²)) denial-of-service via a single long dotted key, table header, or inline-table key. A ~100KB crafted document causes a multi-second synchronous hang; a ~200KB document crashes the Node.

Published Updated

At a glance

Exploited
Not known
Severity
8.7 High (CVSS 4.0)
Chance of exploitation
0.4% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: toml: 5.0.1. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-9j65-hcg3-gc64 (opens a new tab)

What happened

## Summary

`toml.parse()` is vulnerable to a quadratic-complexity (O(n²)) denial-of-service via a single long dotted key, table header, or inline-table key. A ~100KB crafted document causes a multi-second synchronous hang; a ~200KB document crashes the Node.js process outright with an uncatchable out-of-memory error.

This is a separate, unpatched code path from the previously fixed stack-overflow DoS (`GHSA-82x6-q7mm-w9cf`) — it requires no array/inline-table nesting at all, and is confirmed unaffected by the `maxDepth` option that fixed that earlier issue.

## Affected component / version

Continue reading

- Package: `toml` (npm), repository `BinaryMuse/toml-node` - Functions: `assign()`, `deepRef()`, `setNestedKey()` in `lib/compiler.js` - Confirmed present in the audited checkout at commit `1b2ac40` (2026-07-16), one commit past the `v5.0.0` tag (a changelog-only change) — i.e. present in `v5.0.0`, the latest release.

Not exhaustively verified against every prior release, but the affected functions are unrelated to `v5.0.0`'s BigInt/Temporal changes (per `CHANGELOG.md`), so the defect likely predates that release as well.

## Details

`toml.parse(input, options)` (`index.js:5-9`) forwards the caller-supplied string to `parser.parse()` and then `compiler.compile()` with no length or structural validation. Inside `lib/compiler.js`, three separate functions each walk a dotted key's segments in a `for` loop and, on **every** iteration, recompute the full path-prefix string from scratch:

- `assign()` (lines 69-107, the sink at line 81): `var intermediatePath = makeFullPath(keys.slice(0, i + 1));` — reached for top-level dotted-key assignments like `a.b.c = 1`. - `deepRef()` (lines 247-281, the sink at line 252): the identical pattern via `pathKey(keys.slice(0, i + 1))` — reached from table headers `[a.b.c]` and array-of-tables `[[a.b.c]]` via `setPath()`/`addTableArray()`.

- `setNestedKey()` (lines 184-202, the sink at line 187): the identical pattern — reached from inline-table dotted keys like `t = { a.b.c = 1 }`.

`keys.slice(0, i + 1)` allocates a new array of length `i`; `pathKey()`/`makeFullPath()` (lines 311-317) then does `.map(quoteDottedString).join(".")`, also O(i). Since this runs on every one of the `n` segments of a dotted key, total work is `O(1 + 2 + ... + n) = O(n²)`, not `O(n)`. The string is computed unconditionally on the happy path (only ever *used* if an error is about to be thrown), so there is no early exit that makes this cheap in practice.

No limit exists anywhere on dotted-key segment count: `dot_ended_table_key_part+` and `inline_dot_key_part+` in `src/toml.pegjs` (lines 122, 311) are unbounded `+` repetitions, parsed iteratively rather than through the grammar's `value` rule — so the existing `MAX_DEPTH`/`maxDepth` nesting guard (`src/toml.pegjs:141-151`, enforced in the generated `lib/parser.js:1022`) does not apply to key length at all.

We confirmed this directly: setting `options.maxDepth: 1` (the strictest possible value) against a 16,000-segment key produced no measurable timing difference from the unrestricted case.

## Proof of Concept

```js const toml = require('toml');

// n-segment dotted key: "k0.k1.k2. ... .k{n-1} = 1" function segKey(n) { const parts = []; for (let i = 0; i < n; i++) parts.push('k' + i); return parts.join('.') + ' = 1\n'; }

// ~100.9 KB input -- takes ~6.6-6.8 seconds toml.parse(segKey(16000));

// ~200 KB input -- crashes the Node process: // "FATAL ERROR: Ineffective mark-compacts near heap limit - JavaScript heap out of memory" toml.parse(segKey(32000)); ```

Measured timings (Node v22, direct execution against this repo):

| n (segments) | input size | time | |---|---|---| | 1,000 | ~4.9 KB | 34 ms | | 8,000 | ~46.9 KB | 1.6 s | | 16,000 | ~100.9 KB | 6.8 s | | 32,000 | ~200 KB | **process crash (OOM)** |

Doubling `n` from 8,000→16,000 roughly quadruples runtime (~4.2x), the signature of O(n²) rather than the expected O(n) (~2x). Independently reproduced with the identical scaling signature for the table-header variant (`[k0. ... .k15999]`, exercising `deepRef()`) and the inline-table variant (`t = { k0. ... .k15999 = 1 }`, exercising `setNestedKey()`).

We also generalized this into a property-based fuzzing harness (fast-check, run under Node) that automatically tests the "doubling input size should not more than roughly double parse time" invariant across 12 structural dimensions of the grammar/compiler; it independently re-flags all three code paths above on every run, with no additional dimension confirmed vulnerable after follow-up investigation. The harness is available on request.

## Impact

Node.js is single-threaded — a synchronous multi-second-to-crashing `parse()` call blocks the entire event loop of the process calling it, stalling every other request/operation that process is handling, not just the attacker's own.

At the upper end this is not merely a hang: an uncaught, process-terminating out-of-memory crash from a ~200KB attacker-supplied string is a full denial of service requiring no authentication — just the ability to get one string parsed by an application using this library (config upload, API request body, imported manifest, or any of this library's intended use cases).

## Suggested remediation

Build the path prefix as an incrementally-extended string as the loop walks each segment (append one already-quoted segment per iteration to a running string) instead of re-slicing an array and re-joining the entire prefix from scratch on every iteration. For example, in `assign()`:

```js function assign(node) { var keys = node.key; var value = node.value; var off = node.offset; if (!Array.isArray(keys)) keys = [keys]; var reduced = reduceValueNode(value);

var target = context; var pathStr = pathKey(currentPath); // computed once, not per segment for (var i = 0; i < keys.length - 1; i++) { var k = keys[i]; var quotedK = quoteDottedString(k); var intermediatePath = pathStr ? pathStr + "." + quotedK :

Affected package ranges reported by GitHub: toml: <= 5.0.0

Scores and how they were measured

CVSS base severity

8.7

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.4%

Scored Percentile 30.1%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-9j65-hcg3-gc64 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-9j65-hcg3-gc64, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-114143 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  13. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  14. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-114143, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 22). toml-node: Quadratic-complexity DoS via long dotted keys or table paths in toml.parse() (CVE-2026-114143). https://kevwire.com/record/CVE-2026-114143

MLA

"toml-node: Quadratic-complexity DoS via long dotted keys or table paths in toml.parse() (CVE-2026-114143)." KEVWire, 22 Oct. 2026, kevwire.com/record/CVE-2026-114143.

Chicago

KEVWire. "toml-node: Quadratic-complexity DoS via long dotted keys or table paths in toml.parse() (CVE-2026-114143)." Last modified October 22, 2026. https://kevwire.com/record/CVE-2026-114143.

Evidence summary (plain text)

toml-node: Quadratic-complexity DoS via long dotted keys or table paths in toml.parse() (Oct 22, 2026).
`toml.parse()` is vulnerable to a quadratic-complexity (O(n²)) denial-of-service via a single
long dotted key, table header, or inline-table key. A ~100KB crafted document causes a
multi-second synchronous hang; a ~200KB document crashes the Node.js process outright with an
uncatchable out-of-memory error. This is a separate, unpatched code path from the previously
fixed stack-overflow DoS (`GHSA-82x6-q7mm-w9cf`) — it requires no array/inline-table nesting at
all, and is confirmed unaffected by the `maxDepth` option that fixed that earlier issue.

- Package: `toml` (npm), repository `BinaryMuse/toml-node`
- Functions: `assign()`, `deepRef()`, `setNestedKey()` in `lib/compiler.js`
- Confirmed present in the audited checkout at commit `1b2ac40` (2026-07-16), one commit past
 the `v5.0.0` tag (a changelog-only change) — i.e. present in `v5.0.0`, the latest release.
 Not exhaustively verified against every prior release, but the affected functions are
 unrelated to `v5.0.0`'s BigInt/Temporal changes (per `CHANGELOG.md`), so the defect likely
 predates that release as well.
CVSS 8.7 (version 4.0; evidence as of Oct 22, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-114143).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-114143&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-9j65-hcg3-gc64: https://github.com/advisories/GHSA-9j65-hcg3-gc64
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo1MTozMFrOAAf0Mg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0OToxMlrOAAf0LQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0NzoxN1rOAAf0Kg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0NTozNlrOAAf0Jw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0NTowNVrOAAf0JQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0Mzo0NVrOAAf0Iw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo0MzozMVrOAAf0Ig%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODozNTowMVrOAAZRcw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODozMDoyN1rOAAY_5Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QxODoyOTowNVrOAAfz8g%3D%3D
NVD CVE-2026-114143: https://nvd.nist.gov/vuln/detail/CVE-2026-114143
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=8000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-114143&date=2026-10-26
Record ID: CVE-2026-114143.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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