Update dependency qs to v6.14.1 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
qs	6.11.2 → 6.14.1

GitHub Vulnerability Alerts

CVE-2017-1000048

Affected version of qs are vulnerable to Prototype Pollution because it is possible to bypass the protection. The qs.parse function fails to properly prevent an object's prototype to be altered when parsing arbitrary input. Input containing [ or ] may bypass the prototype pollution protection and alter the Object prototype. This allows attackers to override properties that will exist in all objects, which may lead to Denial of Service or Remote Code Execution in specific circumstances.

Recommendation

Upgrade to 6.0.4, 6.1.2, 6.2.3, 6.3.2 or later.

CVE-2022-24999

qs before 6.10.3 allows attackers to cause a Node process hang because an __ proto__ key can be used. In many typical web framework use cases, an unauthenticated remote attacker can place the attack payload in the query string of the URL that is used to visit the application, such as a[__proto__]=b&a[__proto__]&a[length]=100000000. The fix was backported to qs 6.9.7, 6.8.3, 6.7.3, 6.6.1, 6.5.3, 6.4.1, 6.3.3, and 6.2.4.

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).

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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

v6.14.0

Compare Source

• [New] parse: add throwOnParameterLimitExceeded option (#​517)
• [Refactor] parse: use utils.combine more
• [patch] parse: add explicit throwOnLimitExceeded default
• [actions] use shared action; re-add finishers
• [meta] Fix changelog formatting bug
• [Deps] update side-channel
• [Dev Deps] update es-value-fixtures, has-bigints, has-proto, has-symbols
• [Tests] increase coverage

v6.13.1

Compare Source

• [Fix] stringify: avoid a crash when a filter key is null
• [Fix] utils.merge: functions should not be stringified into keys
• [Fix] parse: avoid a crash with interpretNumericEntities: true, comma: true, and iso charset
• [Fix] stringify: ensure a non-string filter does not crash
• [Refactor] use __proto__ syntax instead of Object.create for null objects
• [Refactor] misc cleanup
• [Tests] utils.merge: add some coverage
• [Tests] fix a test case
• [actions] split out node 10-20, and 20+
• [Dev Deps] update es-value-fixtures, mock-property, object-inspect, tape

v6.13.0

Compare Source

• [New] parse: add strictDepth option (#​511)
• [Tests] use npm audit instead of aud

v6.12.3

Compare Source

• [Fix] parse: properly account for strictNullHandling when allowEmptyArrays
• [meta] fix changelog indentation

v6.12.2

Compare Source

• [Fix] parse: parse encoded square brackets (#​506)
• [readme] add CII best practices badge

v6.12.1

Compare Source

• [Fix] parse: Disable decodeDotInKeys by default to restore previous behavior (#​501)
• [Performance] utils: Optimize performance under large data volumes, reduce memory usage, and speed up processing (#​502)
• [Refactor] utils: use +=
• [Tests] increase coverage

v6.12.0

Compare Source

• [New] parse/stringify: add decodeDotInKeys/encodeDotKeys options (#​488)
• [New] parse: add duplicates option
• [New] parse/stringify: add allowEmptyArrays option to allow [] in object values (#​487)
• [Refactor] parse/stringify: move allowDots config logic to its own variable
• [Refactor] stringify: move option-handling code into normalizeStringifyOptions
• [readme] update readme, add logos (#​484)
• [readme] stringify: clarify default arrayFormat behavior
• [readme] fix line wrapping
• [readme] remove dead badges
• [Deps] update side-channel
• [meta] make the dist build 50% smaller
• [meta] add sideEffects flag
• [meta] run build in prepack, not prepublish
• [Tests] parse: remove useless tests; add coverage
• [Tests] stringify: increase coverage
• [Tests] use mock-property
• [Tests] stringify: improve coverage
• [Dev Deps] update @ljharb/eslint-config , aud, has-override-mistake, has-property-descriptors, mock-property, npmignore, object-inspect, tape
• [Dev Deps] pin glob, since v10.3.8+ requires a broken jackspeak
• [Dev Deps] pin jackspeak since 2.1.2+ depends on npm aliases, which kill the install process in npm < 6

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