CVE-2026-44055: Netatalk RCE Vulnerability

CVE-2026-44055 Overview

CVE-2026-44055 is an OS command injection vulnerability [CWE-78] affecting Netatalk versions 3.1.4 through 4.4.2. The flaw stems from a logic error involving bitwise OR operations within the Netatalk codebase. A remote authenticated attacker can exploit the issue to inject operating system commands and execute arbitrary code on the host running the Netatalk service.

Netatalk implements the Apple Filing Protocol (AFP) on Unix-like systems, allowing macOS clients to access network file shares. Successful exploitation grants attackers code execution within the context of the Netatalk service process.

Critical Impact

Authenticated remote attackers can execute arbitrary OS commands on systems running vulnerable Netatalk versions, leading to full compromise of the file server.

Affected Products

• Netatalk 3.1.4 through 3.x.x (all releases in this range)
• Netatalk 4.0.0 through 4.4.2
• Unix and Linux distributions packaging vulnerable Netatalk builds

Discovery Timeline

• 2026-05-21 - CVE CVE-2026-44055 published to the National Vulnerability Database (NVD)
• 2026-05-21 - Last updated in NVD database

Technical Details for CVE-2026-44055

Vulnerability Analysis

The vulnerability resides in Netatalk's handling of operations that combine values using bitwise OR. A flaw in this logic causes input-derived data to flow into a path where it is interpreted as part of an OS command string. The result is an OS command injection condition classified under [CWE-78].

Netatalk runs with elevated privileges on most deployments because the daemon manages file shares and user sessions. Code execution through this flaw therefore inherits the privileges of the Netatalk process, which in many environments is root. The Netatalk advisory documents the affected version range as 3.1.4 through 4.4.2.

Root Cause

The root cause is a logic error in code that uses bitwise OR (|) operations. The faulty logic fails to enforce the validation or sanitization conditions the developer intended. As a result, attacker-controlled data reaches a function that dispatches OS commands without proper escaping. See the Netatalk Security Advisory for vendor technical details.

Attack Vector

Exploitation requires network access to the Netatalk service and valid credentials, since the attack vector is Network with Low privileges required. The attacker authenticates to the AFP service, then sends a crafted protocol request that triggers the vulnerable code path. The injected command executes on the server. Attack complexity is rated High, indicating the attacker must satisfy additional conditions to reliably trigger the flaw.

No verified public proof-of-concept exploit code is available at this time. Refer to the vendor advisory for technical details on the affected functions and request types.

Detection Methods for CVE-2026-44055

Indicators of Compromise

• Unexpected child processes spawned by the afpd or netatalk daemon, particularly shells (/bin/sh, /bin/bash) or interpreters (python, perl)
• Outbound network connections initiated by the Netatalk daemon to external addresses
• New or modified files in system directories owned by the user running the Netatalk service
• Anomalous AFP authentication events followed immediately by process creation activity

Detection Strategies

• Monitor process trees where afpd is the parent process of command interpreters or scripting engines
• Inspect AFP protocol traffic for unusually structured requests containing shell metacharacters such as ;, |, `, or $()
• Correlate authenticated AFP sessions with subsequent privileged file system or process activity on the host

Monitoring Recommendations

• Enable auditd or equivalent process auditing on Unix hosts running Netatalk and forward events to a centralized analytics platform
• Track Netatalk version inventory across the environment and flag any host running versions 3.1.4 through 4.4.2
• Alert on Netatalk service crashes, restarts, or configuration file modifications that may indicate exploitation attempts

How to Mitigate CVE-2026-44055

Immediate Actions Required

• Identify all hosts running Netatalk and confirm the installed version against the affected range 3.1.4 through 4.4.2
• Restrict network access to the AFP service (TCP 548) to trusted management networks using host or network firewalls
• Audit Netatalk user accounts and remove any that are unused or have weak passwords, since exploitation requires authentication
• Apply the vendor-supplied patch as soon as it is available in your distribution

Patch Information

Consult the Netatalk Security Advisory for the fixed release version and patch details. Upgrade to a version newer than 4.4.2 once the vendor publishes a fixed build, or apply distribution backports as they become available.

Workarounds

• Disable the Netatalk service on hosts where AFP file sharing is not required
• Limit AFP service exposure to internal VLANs and block the protocol at the network perimeter
• Enforce strong authentication and rotate credentials for all AFP users to reduce the pool of attackers who could meet the authentication prerequisite
• Run the Netatalk daemon under a dedicated low-privilege account where the deployment supports it, to limit the impact of command execution

# Example: disable and stop the Netatalk service on systemd-based Linux
sudo systemctl stop netatalk
sudo systemctl disable netatalk

# Example: restrict AFP (TCP 548) to a trusted subnet using iptables
sudo iptables -A INPUT -p tcp --dport 548 -s 10.0.0.0/24 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 548 -j DROP