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build(deps-dev): Bump dependency js-yaml to v5.2.2 [SECURITY] - #315

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Jul 27, 2026
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build(deps-dev): Bump dependency js-yaml to v5.2.2 [SECURITY]#315
renovate[bot] merged 1 commit into
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renovate/npm-js-yaml-vulnerability

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This PR contains the following updates:

Package Change Age Confidence
js-yaml 5.2.15.2.2 age confidence

js-yaml: Exponential parsing time in flow collections leads to denial of service

GHSA-pm4m-ph32-ghv5

More information

Details

Summary

Parsing a small YAML document can take exponential time. An application that calls load() or loadAll() on untrusted input can be hung by a payload under 200 bytes.

Details

When an entry in a flow sequence turns out to be a key: value pair, the parser rewinds and parses that entry a second time as the key.
If the key is itself a nested flow sequence of the same shape, every level is parsed twice, so the total work is O(2^n) in the nesting depth. The default maxDepth of 100 does not help, because the time is already unmanageable at about 30 to 40 levels.

Root cause, potentially the: readFlowCollection in parser.ts, the restoreState followed by a second parseNode further down.

PoC
const yaml = require('js-yaml')
const n = 30
yaml.load('[ '.repeat(n) + '1' + ' ]: 0'.repeat(n))

With default options: 22 levels takes about 1 second, 26 levels about 17 seconds, 30 levels over 2 minutes. The input stays under 200 bytes and grows linearly with n.

Impact

Denial of service. A single small request can keep one CPU busy for minutes or longer and blocks the Node event loop, so one request can stall the whole process. No anchors, aliases, merges, tags, or non default options are required, and it reproduces on the default schema.

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

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


Release Notes

nodeca/js-yaml (js-yaml)

v5.2.2

Compare Source

Fixed
  • Quote flow scalars where a colon precedes a flow indicator, #​773.
Security
  • Avoid exponential parsing time for nested flow sequence pairs.

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renovate Bot enabled auto-merge (squash) July 27, 2026 00:31
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renovate Bot merged commit d24e661 into main Jul 27, 2026
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renovate Bot deleted the renovate/npm-js-yaml-vulnerability branch July 27, 2026 12:44
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