Update dependency js-yaml to v5.4.1 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
js-yaml	5.2.2 → 5.4.1

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

GHSA-r3ph-w7gj-g6xm

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

When merge keys are enabled, an attacker can submit a relatively small YAML document that causes prolonged CPU consumption despite the default maxTotalMergeKeys limit.

Fix

Count every merge source mapping as one budget unit in addition to counting its keys.

Severity

• CVSS Score: 5.3 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

• https://github.com/nodeca/js-yaml/security/advisories/GHSA-r3ph-w7gj-g6xm
• https://github.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef480
• https://github.com/nodeca/js-yaml/releases/tag/5.4.1
• https://github.com/advisories/GHSA-r3ph-w7gj-g6xm

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

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Release Notes

nodeca/js-yaml (js-yaml)

v5.4.1

Compare Source

v5.4.0

Compare Source

Added

• Added the scalarStyleRules dumper option to customize string formatting.
  See Scalar styling for details.

Changed

• [breaking] Flattened the low-level AST node style representation. Scalar
  and collection nodes now use SCALAR_STYLE and COLLECTION_STYLE values;
  explicit tags use the separate tagged property. Alias nodes now contain
  only kind and anchor. This only affects code that directly constructs or
  edits AST nodes.
• [breaking] The sortKeys option was rewritten using AST mutation to avoid
  side effects.
• Reworked scalar style selection. This can change formatting without changing
  loaded values; in particular, whitespace-only strings are now double-quoted.

Fixed

• Accept a byte order mark at the start of each document in a stream, #​791.
• Produce valid flow mappings with quoteFlowKeys and flowSkipColonSpace,
  including alias and property-only keys, #​786.
• Preserve empty scalar items when converting block sequences to flow style.
• Do not apply the 1024-character simple-key limit to flow mapping keys.
• Count Unicode code points, rather than UTF-16 code units, for the
  1024-character simple-key limit.
• Add an explicit document-end marker after keep-chomped block scalars when
  needed to preserve trailing newlines.

v5.3.0

Compare Source

This release focuses on reworking the documentation and making small
architectural improvements before moving forward.

Added

• Added completely new documentation.
• Exported DUMP_SCHEMA, the default schema used by the dumper.
• Added YAMLException.throwAt() for throwing an error at a source position.

Changed

• Changed flat constant exports to grouped exports: EVENT_ID, SCALAR_STYLE,
  COLLECTION_STYLE, and CHOMPING_MODE, along with their value types. The old
  exports are still preserved, but deprecated.
• Made identify mandatory for custom tag definitions. Use
  identify: () => false for load-only tags.

Deprecated

• Deprecated flat constant exports. Use grouped ones instead.

Removed

• Removed the MERGE_KEY export (not used anymore after last fixes).

Fixed

• Validate << sequence items at merge time, so aliased merge sources are
  checked too.
• Resolve << outside of a mapping key as the plain string '<<', matching
  v4, instead of leaking an internal symbol into the result.

v5.2.3

Compare Source

Fixed

• Prevent prototype fallback when resolving tags and mapping entries, #​782.
• Resolve !!timestamp years 0000-0099 correctly, #​775.
• Preserve implicit null mapping values before document markers and reject
  unpaired mapping event streams, #​784.
• Preserve folded scalar values with tab-indented lines when round-tripping a
  parsed AST through present(); dump() and loading are unaffected, #​780.

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