{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-04-25T00:16:44.089","vulnerabilities":[{"cve":{"id":"CVE-2026-2391","sourceIdentifier":"7ffcee3d-2c14-4c3e-b844-86c6a321a158","published":"2026-02-12T05:17:11.187","lastModified":"2026-02-24T20:13:51.837","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"### Summary\nThe `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).\n\n### Details\nWhen 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.\n\n**Vulnerable code** (lib/parse.js: lines ~40-50):\n```js\nif (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {\n    return val.split(',');\n}\n\nif (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {\n    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');\n}\n\nreturn val;\n```\nThe `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).\n\n### PoC\n**Test 1 - Basic bypass:**\n```\nnpm install qs\n```\n\n```js\nconst qs = require('qs');\n\nconst payload = 'a=' + ','.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\nconst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\n\ntry {\n  const result = qs.parse(payload, options);\n  console.log(result.a.length);  // Outputs: 26 (bypass successful)\n} catch (e) {\n  console.log('Limit enforced:', e.message);  // Not thrown\n}\n```\n**Configuration:**\n- `comma: true`\n- `arrayLimit: 5`\n- `throwOnLimitExceeded: true`\n\nExpected: Throws \"Array limit exceeded\" error.\nActual: Parses successfully, creating an array of length 26.\n\n\n### Impact\nDenial of Service (DoS) via memory exhaustion."},{"lang":"es","value":"### Resumen\nLa opción `arrayLimit` en qs no aplica límites para valores separados por comas cuando `comma: true` está habilitado, permitiendo a los atacantes causar denegación de servicio a través del agotamiento de memoria. Esto es un bypass de la aplicación del límite de array, similar al bypass de notación de corchetes abordado en GHSA-6rw7-vpxm-498p (CVE-2025-15284).\n\n### Detalles\nCuando la opción `comma` se establece en `true` (no es el valor predeterminado, pero es configurable en las aplicaciones), qs permite analizar cadenas separadas por comas como arrays (por ejemplo, `?param=a,b,c` se convierte en `['a', 'b', 'c']`). Sin embargo, la verificación de límite para `arrayLimit` (predeterminado: 20) y la opción throwOnLimitExceeded ocurren después de la lógica de manejo de comas en `parseArrayValue`, lo que permite un bypass. Esto permite la creación de arrays arbitrariamente grandes a partir de un solo parámetro, lo que lleva a una asignación excesiva de memoria.\n\nCódigo vulnerable (lib/parse.js: líneas ~40-50):\n```js\nif (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {\n    return val.split(',');\n}\n\nif (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {\n    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');\n}\n\nreturn val;\n```\nEl `split(',')` devuelve el array inmediatamente, omitiendo la verificación de límite subsiguiente. La fusión posterior a través de `utils.combine` no evita la asignación, incluso si marca desbordamientos para arrays dispersos. Esta discrepancia permite a los atacantes enviar un solo parámetro con millones de comas (por ejemplo, `?param=,,,,,,,,...`), asignando arrays masivos en memoria sin activar los límites. Bypassea la intención de `arrayLimit`, que se aplica correctamente para las notaciones indexadas (`a[0]=`) y de corchetes (`a[]=`) (esta última corregida en v6.14.1 según GHSA-6rw7-vpxm-498p).\n\n### PoC\nPrueba 1 - Bypass básico:\n```\nnpm install qs\n```\n\n```js\nconst qs = require('qs');\n\nconst payload = 'a=' + ','.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\nconst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\n\ntry {\n  const result = qs.parse(payload, options);\n  console.log(result.a.length);  // Outputs: 26 (bypass successful)\n} catch (e) {\n  console.log('Limit enforced:', e.message);  // Not thrown\n}\n```\nConfiguración:\n- `comma: true`\n- `arrayLimit: 5`\n- `throwOnLimitExceeded: true`\n\nEsperado: Lanza el error 'Array limit exceeded'.\nReal: Analiza con éxito, creando un array de longitud 26.\n\n### Impacto\nDenegación de Servicio (DoS) a través del agotamiento de memoria."}],"metrics":{"cvssMetricV40":[{"source":"7ffcee3d-2c14-4c3e-b844-86c6a321a158","type":"Secondary","cvssData":{"version":"4.0","vectorString":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":6.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"cvssMetricV31":[{"source":"7ffcee3d-2c14-4c3e-b844-86c6a321a158","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","baseScore":3.7,"baseSeverity":"LOW","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":2.2,"impactScore":1.4},{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}]},"weaknesses":[{"source":"7ffcee3d-2c14-4c3e-b844-86c6a321a158","type":"Secondary","description":[{"lang":"en","value":"CWE-20"}]},{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"NVD-CWE-noinfo"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:qs_project:qs:*:*:*:*:*:node.js:*:*","versionStartIncluding":"6.7.0","versionEndExcluding":"6.14.2","matchCriteriaId":"94E3C0EE-F451-4D63-8670-0E428FED05AD"}]}]}],"references":[{"url":"https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482","source":"7ffcee3d-2c14-4c3e-b844-86c6a321a158","tags":["Patch"]},{"url":"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883","source":"7ffcee3d-2c14-4c3e-b844-86c6a321a158","tags":["Exploit","Vendor Advisory"]},{"url":"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","tags":["Exploit","Vendor Advisory"]}]}}]}