Skip to content

fix(deps): update dependency qs to v6.14.1 [security] - autoclosed#200

Closed
renovate[bot] wants to merge 1 commit intomainfrom
renovate/npm-qs-vulnerability
Closed

fix(deps): update dependency qs to v6.14.1 [security] - autoclosed#200
renovate[bot] wants to merge 1 commit intomainfrom
renovate/npm-qs-vulnerability

Conversation

@renovate
Copy link
Copy Markdown
Contributor

@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 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

📅 Schedule: Branch creation - "" (UTC), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.


  • If you want to rebase/retry this PR, check this box

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

@vercel
Copy link
Copy Markdown

vercel Bot commented Jan 1, 2026

The latest updates on your projects. Learn more about Vercel for GitHub.

Project Deployment Actions Updated (UTC)
sentiment Ready Ready Preview, Comment Feb 2, 2026 9:09pm

@coderabbitai
Copy link
Copy Markdown

coderabbitai Bot commented Jan 1, 2026

Important

Review skipped

Bot user detected.

To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

  • 🔍 Trigger a full review

Comment @coderabbitai help to get the list of available commands and usage tips.

@codecov
Copy link
Copy Markdown

codecov Bot commented Jan 1, 2026

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 25.89%. Comparing base (aa9d8af) to head (9643758).

Additional details and impacted files
@@           Coverage Diff           @@
##             main     #200   +/-   ##
=======================================
  Coverage   25.89%   25.89%           
=======================================
  Files          45       45           
  Lines         336      336           
  Branches       53       54    +1     
=======================================
  Hits           87       87           
  Misses        249      249           

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

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
  • 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

@renovate renovate Bot force-pushed the renovate/npm-qs-vulnerability branch from 9643758 to 6ac82a3 Compare February 2, 2026 21:08
@renovate renovate Bot changed the title fix(deps): update dependency qs to v6.14.1 [security] fix(deps): update dependency qs to v6.14.1 [security] - autoclosed Feb 5, 2026
@renovate renovate Bot closed this Feb 5, 2026
@renovate renovate Bot deleted the renovate/npm-qs-vulnerability branch February 5, 2026 02:29
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Projects

None yet

Development

Successfully merging this pull request may close these issues.

1 participant