Echo has a Windows path traversal via backslash in middleware.Static default filesystem_CVE-2026-25766

{
    "lastseen": "",
    "description": "Echo is a Go web framework. In versions 5.0.0 through 5.0.2 on Windows, Echo\u2019s `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.",
    "published": "2026-02-19T15:49:02.402Z",
    "modified": "2026-02-19T15:49:02.402Z",
    "type": "cve",
    "title": "Echo has a Windows path traversal via backslash in middleware.Static default filesystem",
    "source": "GitHub_M",
    "references": "https://github.com/labstack/echo/security/advisories/GHSA-pgvm-wxw2-hrv9\nhttps://github.com/labstack/echo/pull/2891\nhttps://github.com/labstack/echo/commit/b1d443086ea27cf51345ec72a71e9b7e9d9ce5f1",
    "id": "CVE-2026-25766",
    "bulletinFamily": "",
    "cwe": [
        "CWE-22"
    ],
    "cvelist": null,
    "sourceData": "labstack echo >= 5.0.0, < 5.0.3",
    "sourceHref": "",
    "cvss": {
        "score": 5.3,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "echo",
    "version": ">= 5.0.0, < 5.0.3",
    "vendor": "labstack",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}