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@renovate renovate bot commented Dec 31, 2025

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 does not enforce limits for bracket notation (a[]=1&a[]=2), allowing attackers to cause denial-of-service via memory exhaustion. Applications using arrayLimit for DoS protection are vulnerable.

Details

The arrayLimit option only checks limits for indexed notation (a[0]=1&a[1]=2) but completely bypasses 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

Test 1 - Basic bypass:

npm install qs
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)

Test 2 - DoS demonstration:

const qs = require('qs');
const attack = 'a[]=' + Array(10000).fill('x').join('&a[]=');
const result = qs.parse(attack, { arrayLimit: 100 });
console.log(result.a.length);  // Output: 10000 (should be max 100)

Configuration:

  • arrayLimit: 5 (test 1) or arrayLimit: 100 (test 2)
  • Use bracket notation: a[]=value (not indexed a[0]=value)

Impact

Denial of Service via memory exhaustion. Affects applications using qs.parse() with user-controlled input and arrayLimit for protection.

Attack scenario:

  1. Attacker sends HTTP request: GET /api/search?filters[]=x&filters[]=x&...&filters[]=x (100,000+ times)
  2. Application parses with qs.parse(query, { arrayLimit: 100 })
  3. qs ignores limit, parses all 100,000 elements into array
  4. Server memory exhausted → application crashes or becomes unresponsive
  5. Service unavailable for all users

Real-world impact:

  • Single malicious request can crash server
  • No authentication required
  • Easy to automate and scale
  • Affects any endpoint parsing query strings with bracket notation

Suggested Fix

Add arrayLimit validation to the bracket notation handler. The code already calculates currentArrayLength at line 147-151, but it's not used in the bracket notation handler at line 159.

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

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

Fixed code:

if (root === '[]' && options.parseArrays) {
    // Use currentArrayLength already calculated at line 147-151
    if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
        throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
    }
    
    // If limit exceeded and not throwing, convert to object (consistent with indexed notation behavior)
    if (currentArrayLength >= options.arrayLimit) {
        obj = options.plainObjects ? { __proto__: null } : {};
        obj[currentArrayLength] = leaf;
    } else {
        obj = options.allowEmptyArrays && (leaf === '' || (options.strictNullHandling && leaf === null))
            ? []
            : utils.combine([], leaf);
    }
}

This makes bracket notation behaviour consistent with indexed notation, enforcing arrayLimit and converting to object when limit is exceeded (per README documentation).


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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@socket-security
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Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff Package Supply Chain
Security
Vulnerability Quality Maintenance License
Updatedqs@​6.14.0 ⏵ 6.14.1100100 +1610089100

View full report

@pkg-pr-new
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pkg-pr-new bot commented Dec 31, 2025

Open in StackBlitz

npm i https://pkg.pr.new/node-modules/urllib@630

commit: 4dc431a

@codspeed-hq
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codspeed-hq bot commented Dec 31, 2025

CodSpeed Performance Report

Merging #630 will improve performance by 55.33%

Comparing renovate/npm-qs-vulnerability (4dc431a) with master (2c55415)

Summary

⚡ 1 improvement
✅ 8 untouched

Benchmarks breakdown

Benchmark BASE HEAD Efficiency
create HttpClient with connect options 314.9 µs 202.7 µs +55.33%

@codecov
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codecov bot commented Dec 31, 2025

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.57%. Comparing base (2c55415) to head (4dc431a).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files
@@           Coverage Diff           @@
##           master     #630   +/-   ##
=======================================
  Coverage   94.57%   94.57%           
=======================================
  Files          14       14           
  Lines        1474     1474           
  Branches      321      321           
=======================================
  Hits         1394     1394           
  Misses         76       76           
  Partials        4        4           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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@renovate renovate bot changed the title chore(deps): update dependency qs to v6.14.1 [security] chore(deps): update dependency qs to v6.14.1 [security] - autoclosed Dec 31, 2025
@renovate renovate bot closed this Dec 31, 2025
@renovate renovate bot deleted the renovate/npm-qs-vulnerability branch December 31, 2025 09:11
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