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CVE-2026-27590

Estado: AnalizadaAlta (8.9)—

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's FastCGI path splitting logic computes the split index on a lowercased copy of the request path and then uses that byte index to slice the original path. This is unsafe for Unicode because `strings.ToLower()` can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect `SCRIPT_NAME`/`SCRIPT_FILENAME` and `PATH_INFO`, potentially causing a request that contains `.php` to execute a different on-disk file than intended (path confusion). In setups where an attacker can control file contents (e.g., upload features), this can lead to unintended PHP execution of non-.php files (potential RCE depending on deployment). Version 2.11.1 fixes the issue.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad en aplicación web expuesta (Caddy) de procesamiento inseguro de rutas Unicode que permite ejecución remota de código PHP no autorizado sin autenticación (AV:N, PR:N, UI:N). CWE-20 (validación inadecuada) justifica el impacto de ejecución.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account ManagementVulnerability ScanningRestrict Web-Based ContentNetwork SegmentationLimit Software InstallationLimit Access to Resource Over Network

Tecnologías afectadas (1)

Caddyserver — Caddy

CWE

Referencias

JSON original (NVD)

Mostrar
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  "id": "CVE-2026-27590",
  "cveTags": [],
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          "id": "CVE-2026-27590",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-02-27T20:51:50.628047Z"
        }
      }
    ],
    "cvssMetricV31": [
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        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
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          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 8.9,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/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",
          "exploitMaturity": "PROOF_OF_CONCEPT",
          "providerUrgency": "NOT_DEFINED",
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          "subIntegrityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "HIGH",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
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          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
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  "affected": [
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      "affectedData": [
        {
          "vendor": "caddyserver",
          "product": "caddy",
          "versions": [
            {
              "status": "affected",
              "version": "< 2.11.1"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-02-24T17:29:04.493",
  "references": [
    {
      "url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.1",
      "tags": [
        "Release Notes"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g",
      "tags": [
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        "Vendor Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
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          "lang": "en",
          "value": "CWE-20"
        },
        {
          "lang": "en",
          "value": "CWE-180"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's FastCGI path splitting logic computes the split index on a lowercased copy of the request path and then uses that byte index to slice the original path. This is unsafe for Unicode because `strings.ToLower()` can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect `SCRIPT_NAME`/`SCRIPT_FILENAME` and `PATH_INFO`, potentially causing a request that contains `.php` to execute a different on-disk file than intended (path confusion). In setups where an attacker can control file contents (e.g., upload features), this can lead to unintended PHP execution of non-.php files (potential RCE depending on deployment). Version 2.11.1 fixes the issue."
    },
    {
      "lang": "es",
      "value": "Caddy es una plataforma de servidor extensible que utiliza TLS por defecto. Antes de la versión 2.11.1, la lógica de división de rutas FastCGI de Caddy calcula el índice de división en una copia en minúsculas de la ruta de la solicitud y luego utiliza ese índice de bytes para segmentar la ruta original. Esto no es seguro para Unicode porque `strings.ToLower()` puede cambiar la longitud de bytes UTF-8 para algunos caracteres. Como resultado, Caddy puede derivar un `SCRIPT_NAME`/`SCRIPT_FILENAME` y `PATH_INFO` incorrectos, lo que podría causar que una solicitud que contiene .php ejecute un archivo en disco diferente al previsto (confusión de rutas). En configuraciones donde un atacante puede controlar el contenido de los archivos (por ejemplo, funciones de carga), esto puede llevar a la ejecución no intencionada de PHP de archivos que no son .php (RCE potencial dependiendo de la implementación). La versión 2.11.1 corrige el problema."
    }
  ],
  "lastModified": "2026-06-17T10:27:21.350",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "9AD1B432-AFA3-4A05-A687-F6092CDB6498",
              "versionEndExcluding": "2.11.1"
            }
          ],
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        }
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  "sourceIdentifier": "security-advisories@github.com"
}