chore(deps): update dependency qs to v6.14.2 [security] by renovate[bot] · Pull Request #96 · mjolnirjs/yab

renovate · 2023-05-28T10:01:38Z

This PR contains the following updates:

Package	Change	Age	Confidence
qs	`6.7.0` → `6.14.2`

qs vulnerable to Prototype Pollution

CVE-2022-24999 / GHSA-hrpp-h998-j3pp

More information

Details

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.

Severity

CVSS Score: 7.5 / 10 (High)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

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

qs's arrayLimit bypass in its bracket notation allows DoS via memory exhaustion

CVE-2025-15284 / GHSA-6rw7-vpxm-498p

More information

Details

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.

Severity

CVSS Score: 6.3 / 10 (Medium)
Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

References

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

qs's arrayLimit bypass in comma parsing allows denial of service

CVE-2026-2391 / GHSA-w7fw-mjwx-w883

More information

Details

Summary

The arrayLimit option in qs does not enforce limits for comma-separated values when comma: true is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).

Details

When the comma option is set to true (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., ?param=a,b,c becomes ['a', 'b', 'c']). However, the limit check for arrayLimit (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in parseArrayValue, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.

Vulnerable code (lib/parse.js: lines ~40-50):

if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
    return val.split(',');
}

if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}

return val;

The split(',') returns the array immediately, skipping the subsequent limit check. Downstream merging via utils.combine does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., ?param=,,,,,,,,...), allocating massive arrays in memory without triggering limits. It bypasses the intent of arrayLimit, which is enforced correctly for indexed (a[0]=) and bracket (a[]=) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).

PoC

Test 1 - Basic bypass:

npm install qs

const qs = require('qs');

const payload = 'a=' + ','.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)
const options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };

try {
  const result = qs.parse(payload, options);
  console.log(result.a.length);  // Outputs: 26 (bypass successful)
} catch (e) {
  console.log('Limit enforced:', e.message);  // Not thrown
}

Configuration:

comma: true
arrayLimit: 5
throwOnLimitExceeded: true

Expected: Throws "Array limit exceeded" error.
Actual: Parses successfully, creating an array of length 26.

Impact

Denial of Service (DoS) via memory exhaustion.

Suggested Fix

Move the arrayLimit check before the comma split in parseArrayValue, and enforce it on the resulting array length. Use currentArrayLength (already calculated upstream) for consistency with bracket notation fixes.

Current code (lib/parse.js: lines ~40-50):

if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
    return val.split(',');
}

if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}

return val;

Fixed code:

if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
    const splitArray = val.split(',');
    if (splitArray.length > options.arrayLimit - currentArrayLength) {  // Check against remaining limit
        if (options.throwOnLimitExceeded) {
            throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
        } else {
            // Optionally convert to object or truncate, per README
            return splitArray.slice(0, options.arrayLimit - currentArrayLength);
        }
    }
    return splitArray;
}

if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}

return val;

This aligns behavior with indexed and bracket notations, reuses currentArrayLength, and respects throwOnLimitExceeded. Update README to note the consistent enforcement.

Severity

CVSS Score: 3.7 / 10 (Low)
Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

References

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

Release Notes

ljharb/qs (qs)

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renovate Bot commented May 28, 2023 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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qs vulnerable to Prototype Pollution

Details

Severity

References

qs's arrayLimit bypass in its bracket notation allows DoS via memory exhaustion

Details

Summary

Details

PoC

Impact

Severity

References

qs's arrayLimit bypass in comma parsing allows denial of service

Details

Summary

Details

PoC

Impact

Suggested Fix

Severity

References

Release Notes

Configuration

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renovate Bot commented May 28, 2023 •

edited

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