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@renovate renovate bot commented Jan 1, 2026

This PR contains the following updates:

Package Change Age Confidence
qs 6.14.06.14.1 age confidence

GitHub Vulnerability Alerts

CVE-2025-15284

Summary

The arrayLimit option in qs did not enforce limits for bracket notation (a[]=1&a[]=2), only for indexed notation (a[0]=1). This is a consistency bug; arrayLimit should apply uniformly across all array notations.

Note: The default parameterLimit of 1000 effectively mitigates the DoS scenario originally described. With default options, bracket notation cannot produce arrays larger than parameterLimit regardless of arrayLimit, because each a[]=value consumes one parameter slot. The severity has been reduced accordingly.

Details

The arrayLimit option only checked limits for indexed notation (a[0]=1&a[1]=2) but did not enforce it for bracket notation (a[]=1&a[]=2).

Vulnerable code (lib/parse.js:159-162):

if (root === '[]' && options.parseArrays) {
    obj = utils.combine([], leaf);  // No arrayLimit check
}

Working code (lib/parse.js:175):

else if (index <= options.arrayLimit) {  // Limit checked here
    obj = [];
    obj[index] = leaf;
}

The bracket notation handler at line 159 uses utils.combine([], leaf) without validating against options.arrayLimit, while indexed notation at line 175 checks index <= options.arrayLimit before creating arrays.

PoC

const qs = require('qs');
const result = qs.parse('a[]=1&a[]=2&a[]=3&a[]=4&a[]=5&a[]=6', { arrayLimit: 5 });
console.log(result.a.length);  // Output: 6 (should be max 5)

Note on parameterLimit interaction: The original advisory's "DoS demonstration" claimed a length of 10,000, but parameterLimit (default: 1000) caps parsing to 1,000 parameters. With default options, the actual output is 1,000, not 10,000.

Impact

Consistency bug in arrayLimit enforcement. With default parameterLimit, the practical DoS risk is negligible since parameterLimit already caps the total number of parsed parameters (and thus array elements from bracket notation). The risk increases only when parameterLimit is explicitly set to a very high value.


Release Notes

ljharb/qs (qs)

v6.14.1

Compare Source

  • [Fix] ensure arrayLength applies to [] notation as well
  • [Fix] parse: when a custom decoder returns null for a key, ignore that key
  • [Refactor] parse: extract key segment splitting helper
  • [meta] add threat model
  • [actions] add workflow permissions
  • [Tests] stringify: increase coverage
  • [Dev Deps] update eslint, @ljharb/eslint-config, npmignore, es-value-fixtures, for-each, object-inspect

Configuration

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This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate bot force-pushed the renovate/npm-qs-vulnerability branch from b17e6ed to cb65216 Compare January 19, 2026 17:49
@socket-security
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socket-security bot commented Jan 19, 2026

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff Package Supply Chain
Security
Vulnerability Quality Maintenance License
Addedsplit2@​4.2.01001009680100
Addedlodash@​4.17.2181998689100
Addedyargs-parser@​21.1.19910010084100

View full report

@renovate renovate bot force-pushed the renovate/npm-qs-vulnerability branch from cb65216 to be59942 Compare January 23, 2026 16:59
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