---
cve: "CVE-2026-82562"
severity: "MEDIUM"
cvss: 6.3
epss: "32%"
vendor: "ljharb"
kev: false
exploited: false
published: "2026-08-30 01:20:32"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T15:27:33+02:00"
---

# CVE-2026-82562

> 6.3 MEDIUM · 🧪 PoC

## Beschreibung

### Summary



When `qs.parse` is called with `comma: true` and `throwOnLimitExceeded: true`, a comma-separated value under a bracket-push key (`a[]=1,2,3,4`) is split into an array without being compared against `arrayLimit`, while the same value under a flat key (`a=1,2,3,4`), an indexed key (`a[0]=`), a nested key (`a[b]=`), or a dotted key (`a.b=` with `allowDots`) throws the documented `RangeError`. A single parameter such as `a[]=1,2,2,...` therefore produces an inner array of arbitrary length even though the caller opted into the hard limit. This is the `[]=` key form that the fix for CVE-2026-2391 (qs 6.14.2) did not cover.



### Details



In `lib/parse.js`, a comma-separated value under a `[]=` key is split and then wrapped as a single nested element (`val = [val]`, so that each `a[]=x,y` group counts as one element of the outer array). The `arrayLimit` check that 6.14.2 added for comma values runs after that wrap, so for `[]=` parts it only ever saw the wrapper of length 1. 6.15.3 added a pre-split comma count so that an oversized value throws before it is allocated, but gated it on an `isFlatArrayValue` flag that `parseValues` set to `false` for any part containing `[]=`, and did not pass it for object-valued input, so the gap remained.



#### PoC



```js



var qs = require('qs');



var options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true };



qs.parse('a=1,2,3,4', options);   // RangeError: Array limit exceeded. Only 3 elements allowed in an array.



qs.parse('a[]=1,2,3,4', options); // { a: [ [ '1', '2', '3', '4' ] ] }  (no throw)



qs.parse('a[]=' + '1,'.repeat(1000000) + '1', { comma: true, arrayLimit: 20, throwOnLimitExceeded: true });



// no throw; a 1,000,001-element inner array is allocated



```



#### Fix



`lib/parse.js`, applied in 8859c37 on `main` and released as v6.16.0: the `isFlatArrayValue` gate is removed, so every comma-split value is counted against `arrayLimit` before splitting regardless of key form. An in-limit group under `a[]=` still counts as one element of the outer array, and the default (`throwOnLimitExceeded: false`) path is unchanged.



### Affected versions



`>=6.14.2

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 18d085e919dae70c8f1b200ab99323058edab2c2 (Commit)
- 5cf516c0dd557d85d5f18d4a916c96cd9cfc2305 (Commit)

## Referenzen

- <https://github.com/ljharb/qs/security/advisories/GHSA-x5fp-wj9c-mxmx>
- <https://github.com/ljharb/qs/commit/8859c37470e11b42b547b275e4e9bd0bc8cc5464>
- <https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-82562) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_