CVE-2026-82562
ADVISORY - githubSummary
Summary
qs v6.15.3 allows bracket-key input to bypass arrayLimit and throwOnLimitExceeded when comma: true. The input a[]=1,2,3,4 succeeds with arrayLimit: 3, while the equivalent plain-key input is rejected.
Affected version tested:
qs v6.15.3
commit 18d085e919dae70c8f1b200ab99323058edab2c2
Details
parseArrayValue() enforces the comma limit only for flat values. The a[] form is marked non-flat, so its comma-separated value is wrapped after parsing and the inner array is not checked. A single parameter can therefore materialize arbitrarily large arrays.
PoC
const qs = require('qs')
const options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true }
const result = qs.parse('a[]=1,2,3,4', options)
console.log(result.a[0].length) // 4; expected RangeError
const big = qs.parse('a[]=' + '1,'.repeat(1000000) + '1', { comma: true, arrayLimit: 20 })
console.log(big.a[0].length) // 1000001
On v6.15.3, the first input parses successfully and the second creates an array with 1,000,001 elements. The equivalent a=1,2,3,4 input throws RangeError as expected.
Impact
An attacker who can supply a query string or form body can bypass configured array limits and force excessive memory allocation, causing denial of service. The limit must be applied after comma splitting and before the resulting array is wrapped.
Common Weakness Enumeration (CWE)
Allocation of Resources Without Limits or Throttling
Allocation of Resources Without Limits or Throttling
GitHub
2.2
CVSS SCORE
6.3medium| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| qs | npm | - | - | >=6.14.2,<=6.15.3 | 6.16.0 |
CVSS:4 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges.
There is no loss of confidentiality within the Vulnerable System.
There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
There is no loss of integrity within the Vulnerable System.
There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
NIST
2.2
CVSS SCORE
6.3mediumDebian
-
Ubuntu
-