CVE-2026-44049: Netatalk RCE Vulnerability

CVE-2026-44049 Overview

CVE-2026-44049 is an out-of-bounds write vulnerability [CWE-787] in the convert_charset() function of Netatalk, an open-source implementation of the Apple Filing Protocol (AFP). The flaw stems from improper null termination of converted character data and affects Netatalk versions 2.0.4 through 4.4.2. A remote authenticated attacker can send crafted character data to trigger memory corruption, leading to arbitrary code execution or denial of service on the host running the AFP service.

Critical Impact

A remote authenticated attacker can execute arbitrary code or crash the Netatalk daemon by sending crafted character data that overflows internal conversion buffers.

Affected Products

• Netatalk 2.0.4 through 2.x
• Netatalk 3.x releases
• Netatalk 4.0.0 through 4.4.2

Discovery Timeline

• 2026-05-21 - CVE-2026-44049 published to the National Vulnerability Database
• 2026-05-21 - Last updated in NVD database

Technical Details for CVE-2026-44049

Vulnerability Analysis

Netatalk provides AFP file sharing for macOS clients on Unix-like systems. The convert_charset() routine converts between character encodings used by AFP clients and the server's local encoding. The vulnerability arises when this routine fails to correctly null-terminate the converted output buffer.

When an attacker supplies crafted multibyte character sequences, the conversion logic writes past the intended boundary of the destination buffer. This out-of-bounds write corrupts adjacent memory inside the afpd or related Netatalk process. Depending on the layout of the corrupted memory, the attacker can crash the daemon or redirect execution to attacker-controlled data.

The attack requires valid authentication to the AFP service, which limits exposure on hardened deployments but remains practical for environments with shared or weakly protected credentials.

Root Cause

The root cause is improper null termination during character set conversion in convert_charset(). The function does not consistently account for the terminator byte when calculating remaining buffer space, allowing a single-byte or multibyte write to land outside the allocated region. This pattern matches [CWE-787] (Out-of-bounds Write).

Attack Vector

The attack vector is network-based. An authenticated AFP client connects to the Netatalk service and submits filenames, share paths, or metadata containing crafted character data that exercises the vulnerable conversion path. No user interaction on the server is required. Successful exploitation grants code execution in the context of the Netatalk service account, which on many deployments runs with elevated privileges to manage shared files.

No public exploit code or proof-of-concept has been observed in the references at the time of publication. See the Netatalk Security Advisory for upstream technical details.

Detection Methods for CVE-2026-44049

Indicators of Compromise

• Unexpected crashes or restarts of afpd, cnid_dbd, or other Netatalk daemons recorded in system logs or coredumps.
• AFP session activity from authenticated users containing unusually long or malformed filename and metadata strings.
• New or unexpected child processes spawned by the Netatalk service account following AFP client connections.

Detection Strategies

• Monitor process integrity for Netatalk binaries and alert on segmentation faults or abnormal termination signals.
• Inspect AFP protocol traffic for oversized or malformed UTF-8, UTF-16, or Mac codepage sequences in filename and resource fork fields.
• Correlate authentication events with subsequent daemon instability to identify abuse of valid credentials.

Monitoring Recommendations

• Enable verbose logging in afp.conf and forward logs to a centralized log management or SIEM platform for retention and analysis.
• Track outbound network connections originating from the Netatalk service account, which should normally have no outbound activity.
• Audit AFP user accounts regularly and disable inactive or shared credentials that increase exposure to authenticated attacks.

How to Mitigate CVE-2026-44049

Immediate Actions Required

• Upgrade Netatalk to a fixed release published after 4.4.2 as listed in the Netatalk Security Advisory.
• Restrict network access to the AFP service (TCP port 548) to trusted client subnets using host firewalls or network ACLs.
• Rotate AFP credentials and enforce strong, unique passwords to reduce the value of any compromised account.

Patch Information

The Netatalk project addresses CVE-2026-44049 in versions released after 4.4.2. Administrators should consult the Netatalk Security Advisory for the exact fixed version, distribution backports, and upgrade guidance. Package maintainers for major Linux distributions and BSD ports typically publish updated builds shortly after upstream releases.

Workarounds

• Disable the Netatalk AFP service on hosts where it is not required until a patched version is deployed.
• Limit AFP exposure to internal management VLANs and block port 548 at the perimeter firewall.
• Reduce the privileges of the Netatalk service account so that successful exploitation does not yield root-equivalent access.

# Configuration example: restrict AFP access with iptables until patched
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

# Temporarily disable the Netatalk service
sudo systemctl stop netatalk
sudo systemctl disable netatalk