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CVE-2026-25766

Estado: AnalizadaMedia (5.3)—

Echo is a Go web framework. In versions 5.0.0 through 5.0.2 on Windows, Echo’s `middleware.Static` using the default filesystem allows path traversal via backslashes, enabling unauthenticated remote file read outside the static root. In `middleware/static.go`, the requested path is unescaped and normalized with `path.Clean` (URL semantics). `path.Clean` does not treat `\` as a path separator, so `..\` sequences remain in the cleaned path. The resulting path is then passed to `currentFS.Open(...)`. When the filesystem is left at the default (nil), Echo uses `defaultFS` which calls `os.Open` (`echo.go:792`). On Windows, `os.Open` treats `\` as a path separator and resolves `..\`, allowing traversal outside the static root. Version 5.0.3 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).

Tecnologías afectadas (1)

Labstack — Echo

CWE

Referencias

JSON original (NVD)

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          "id": "CVE-2026-25766",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-02-19T19:45:33.220477Z"
        }
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          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "LOW"
        },
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        "exploitabilityScore": 3.9
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  "published": "2026-02-19T16:27:15.497",
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      "url": "https://github.com/labstack/echo/commit/b1d443086ea27cf51345ec72a71e9b7e9d9ce5f1",
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    {
      "lang": "en",
      "value": "Echo is a Go web framework. In versions 5.0.0 through 5.0.2 on Windows, Echo’s `middleware.Static` using the default filesystem allows path traversal via backslashes, enabling unauthenticated remote file read outside the static root. In `middleware/static.go`, the requested path is unescaped and normalized with `path.Clean` (URL semantics). `path.Clean` does not treat `\\` as a path separator, so `..\\` sequences remain in the cleaned path. The resulting path is then passed to `currentFS.Open(...)`. When the filesystem is left at the default (nil), Echo uses `defaultFS` which calls `os.Open` (`echo.go:792`). On Windows, `os.Open` treats `\\` as a path separator and resolves `..\\`, allowing traversal outside the static root. Version 5.0.3 fixes the issue."
    },
    {
      "lang": "es",
      "value": "Echo es un marco web de Go. En las versiones 5.0.0 a 5.0.2 en Windows, el `middleware.Static` de Echo que utiliza el sistema de archivos predeterminado permite recorrer rutas mediante barras invertidas, lo que permite la lectura de archivos remotos no autenticados fuera de la raíz estática. En `middleware/static.go`, la ruta solicitada no se escapa y se normaliza con `path.Clean` (semántica de URL). `path.Clean` no trata `\\` como un separador de ruta, por lo que las secuencias `..\\` permanecen en la ruta limpia. La ruta resultante se pasa entonces a `currentFS.Open(...)`. Cuando el sistema de archivos se deja en el valor predeterminado (nil), Echo utiliza `defaultFS`, que llama a `os.Open` (`echo.go:792`). En Windows, `os.Open` trata `\\` como un separador de ruta y resuelve `..\\`, lo que permite el recorrido fuera de la raíz estática. La versión 5.0.3 corrige el problema."
    }
  ],
  "lastModified": "2026-06-17T10:25:11.797",
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