CVE-2026-44062: Netatalk RCE Vulnerability

CVE-2026-44062 Overview

CVE-2026-44062 is an out-of-bounds write vulnerability [CWE-787] in the pull_charset_flags() function of Netatalk, an open-source implementation of the Apple Filing Protocol (AFP). The flaw stems from a missing output length bounds check when processing character set data. A remote authenticated attacker can exploit this issue by sending crafted character set data to a vulnerable server. Successful exploitation allows arbitrary code execution or denial of service against the Netatalk daemon. The vulnerability affects Netatalk versions 2.0.4 through 4.4.2.

Critical Impact

A remote authenticated attacker can execute arbitrary code or trigger a denial of service on Netatalk servers by sending crafted character set data to the vulnerable pull_charset_flags() function.

Affected Products

• Netatalk 2.0.4 through 2.x branches
• Netatalk 3.x releases up to and including 3.x final
• Netatalk 4.x releases up to and including 4.4.2

Discovery Timeline

• 2026-05-21 - CVE-2026-44062 published to NVD
• 2026-05-21 - Last updated in NVD database

Technical Details for CVE-2026-44062

Vulnerability Analysis

The vulnerability resides in the pull_charset_flags() function within Netatalk 2.0.4 through 4.4.2. Netatalk uses this routine to convert character set data between encodings during AFP request handling. The function fails to validate the length of the destination buffer before writing converted output. An attacker who supplies crafted character set data can cause the function to write beyond the bounds of the output buffer.

The issue is classified as [CWE-787] Out-of-Bounds Write. Memory corruption of this type commonly leads to control-flow hijacking when the overwritten region contains return addresses, function pointers, or heap metadata. Exploitation requires authenticated access, which raises the attack complexity but does not eliminate risk in environments where AFP shares are widely accessible.

Root Cause

The root cause is a missing output length bounds check in pull_charset_flags(). The function trusts the size of the converted character data without verifying it against the allocated destination buffer. Multi-byte character set conversions can produce output larger than the input, and without a guard on the destination length, the conversion overruns the buffer.

Attack Vector

The attack vector is network-based and requires valid authentication to the Netatalk service. Once authenticated, an attacker submits an AFP request containing crafted character set data designed to expand during conversion. The oversized output corrupts adjacent memory in the daemon process. Depending on the precision of the corruption, the result is either arbitrary code execution in the context of the Netatalk daemon or a crash producing denial of service.

No public proof-of-concept code has been released. See the Netatalk Security Advisory for technical details.

Detection Methods for CVE-2026-44062

Indicators of Compromise

• Unexpected crashes or restarts of the afpd or netatalk daemon processes, often visible in system logs as segmentation faults.
• Core dumps generated by Netatalk processes containing corrupted stack or heap regions.
• AFP authentication events followed shortly by daemon termination on the same host.

Detection Strategies

• Monitor Netatalk daemon process exit codes and signal terminations, particularly SIGSEGV and SIGABRT, on hosts exposing AFP services.
• Inspect AFP traffic for unusually large or malformed character set fields delivered after successful authentication.
• Correlate authenticated AFP sessions with subsequent daemon restarts to identify candidate exploitation attempts.

Monitoring Recommendations

• Enable verbose logging in afp.conf to record session metadata, including authenticated user, source IP, and request parameters.
• Forward afpd logs and system journal entries to a centralized log platform for correlation with authentication events.
• Track Netatalk version inventory across the fleet to identify hosts still running 2.0.4 through 4.4.2.

How to Mitigate CVE-2026-44062

Immediate Actions Required

• Identify all hosts running Netatalk 2.0.4 through 4.4.2 and prioritize those exposing AFP services to untrusted networks.
• Upgrade Netatalk to a fixed release as specified in the Netatalk Security Advisory.
• Restrict AFP service exposure to trusted network segments and enforce strong authentication policies.

Patch Information

Refer to the Netatalk Security Advisory for the official fixed version and patch details. Apply distribution packages once vendors publish updated builds for affected Netatalk versions.

Workarounds

• Block inbound TCP traffic to the AFP port (548) at the network perimeter where AFP is not required.
• Disable the Netatalk service on hosts where AFP file sharing is not actively used.
• Limit AFP account creation and rotate credentials for any account that does not require active access, reducing the pool of attackers who satisfy the authentication precondition.

# Configuration example: restrict AFP access at the host firewall (iptables)
# Replace 10.0.0.0/24 with your trusted management network
iptables -A INPUT -p tcp --dport 548 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 548 -j DROP

# Or disable Netatalk if AFP is not required
systemctl stop netatalk
systemctl disable netatalk