FKIE_CVE-2026-27199
Vulnerability from fkie_nvd - Published: 2026-02-21 06:17 - Updated: 2026-03-03 17:30
Severity ?
Summary
Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely. This issue has been fixed in version 3.1.6.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| palletsprojects | werkzeug | * |
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"matchCriteriaId": "97FC0575-11B9-4EDE-A4B1-1724FF940BA5",
"versionEndExcluding": "3.1.6",
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"descriptions": [
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"lang": "en",
"value": "Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely. This issue has been fixed in version 3.1.6."
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"lang": "es",
"value": "Werkzeug es una completa biblioteca de aplicaciones web WSGI. Las versiones 3.1.5 e inferiores, la funci\u00f3n safe_join permite nombres de dispositivos de Windows como nombres de archivo si van precedidos por otros segmentos de ruta. Esto fue reportado previamente como GHSA-hgf8-39gv-g3f2, pero el filtrado a\u00f1adido no tuvo en cuenta el hecho de que safe_join acepta rutas con m\u00faltiples segmentos, como example/NUL. La funci\u00f3n send_from_directory utiliza safe_join para servir archivos de forma segura en rutas especificadas por el usuario bajo un directorio. Si la aplicaci\u00f3n se est\u00e1 ejecutando en Windows, y la ruta solicitada termina con un nombre de dispositivo especial, el archivo se abrir\u00e1 con \u00e9xito, pero la lectura se colgar\u00e1 indefinidamente. Este problema ha sido solucionado en la versi\u00f3n 3.1.6."
}
],
"id": "CVE-2026-27199",
"lastModified": "2026-03-03T17:30:17.783",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "NETWORK",
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"baseScore": 5.3,
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"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
"version": "3.1"
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"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
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"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
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"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
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"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
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"valueDensity": "NOT_DEFINED",
"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",
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"vulnerabilityResponseEffort": "NOT_DEFINED"
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"source": "security-advisories@github.com",
"type": "Secondary"
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"published": "2026-02-21T06:17:00.710",
"references": [
{
"source": "security-advisories@github.com",
"tags": [
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"url": "https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338d"
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"url": "https://github.com/pallets/werkzeug/releases/tag/3.1.6"
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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