CVE-2026-44064: Netatalk Information Disclosure Flaw

CVE-2026-44064 Overview

CVE-2026-44064 is an out-of-bounds read vulnerability in the AppleTalk Session Protocol (ASP) session ID handling logic of Netatalk versions 1.3 through 4.4.2. Netatalk is an open-source implementation of the Apple Filing Protocol (AFP) that allows Unix-like systems to serve as file servers for Apple clients. An attacker on an adjacent network can send a crafted ASP request to trigger the flaw. Successful exploitation leads to limited information disclosure from process memory or causes a denial of service through process termination. The issue is tracked under CWE-125: Out-of-bounds Read.

Critical Impact

An adjacent network attacker can crash the Netatalk service or read limited memory contents without authentication, disrupting file sharing services for Apple clients.

Affected Products

• Netatalk 1.3 through 4.4.2
• Systems exposing AFP/ASP services to local network segments
• Unix and Linux file servers running vulnerable Netatalk releases

Discovery Timeline

• 2026-05-21 - CVE CVE-2026-44064 published to NVD
• 2026-05-21 - Last updated in NVD database

Technical Details for CVE-2026-44064

Vulnerability Analysis

The vulnerability resides in Netatalk's processing of ASP session identifiers. ASP is a session-layer protocol within the AppleTalk stack used by AFP to establish and maintain client-server connections. When the server parses an incoming ASP request, it references session ID fields to associate the request with an active session. The flawed logic reads beyond the bounds of the intended buffer when handling crafted session ID values. This out-of-bounds read exposes adjacent process memory to the protocol handler and may dereference invalid memory regions. The consequence is either partial information leakage or an immediate crash of the Netatalk daemon, terminating service for all connected clients.

Root Cause

The root cause is missing or insufficient bounds validation on session ID values supplied in ASP requests. The handler trusts attacker-controlled length or index data and reads from memory positions outside the allocated session structure. This pattern is classified under CWE-125 and commonly arises when protocol parsers assume well-formed input from the network.

Attack Vector

The attack requires network adjacency, meaning the attacker must be on the same broadcast or local network segment as the Netatalk server. No authentication or user interaction is required. The attacker sends a malformed ASP request containing a manipulated session ID field to the AFP listener. The server processes the request, performs the out-of-bounds read, and either returns leaked bytes within a response or crashes. Refer to the Netatalk Security Advisory for protocol-level details and proof-of-concept guidance.

Detection Methods for CVE-2026-44064

Indicators of Compromise

• Unexpected crashes or restarts of the afpd or atalkd daemons in system logs
• Core dumps generated by Netatalk processes following inbound ASP traffic
• Malformed ASP packets observed on TCP port 548 or DDP traffic from unauthorized hosts
• Spikes in failed AFP session establishments from a single adjacent host

Detection Strategies

• Inspect network captures for ASP OpenSession and request packets containing anomalous session ID fields
• Monitor process supervision logs for repeated Netatalk daemon termination and respawn cycles
• Apply intrusion detection signatures that flag oversized or malformed ASP headers on AFP listeners

Monitoring Recommendations

• Log all AFP connection attempts and correlate sources against authorized client inventories
• Alert on segmentation faults or abnormal exit codes from afpd via system auditing tools
• Track ARP and DDP traffic patterns to identify reconnaissance against Netatalk hosts on the local segment

How to Mitigate CVE-2026-44064

Immediate Actions Required

• Upgrade Netatalk to a version later than 4.4.2 that contains the fix referenced in the vendor advisory
• Restrict AFP and ASP service exposure to trusted network segments using host or network firewalls
• Disable Netatalk on systems that do not require AFP file sharing for Apple clients
• Review system logs for prior crashes that may indicate previous exploitation attempts

Patch Information

The Netatalk maintainers have published guidance in the Netatalk Security Advisory for CVE-2026-44064. Administrators should apply the patched release distributed through the project's official channels or their Linux distribution package repositories once available.

Workarounds

• Block inbound traffic to TCP port 548 and DDP protocol traffic at the network boundary from untrusted hosts
• Place Netatalk servers on isolated VLANs accessible only to authorized Apple clients
• Enforce 802.1X or MAC-based network access control to limit who can reach the adjacent network segment
• Temporarily stop the afpd service on hosts where AFP is not in active use

# Configuration example: restrict AFP access with iptables
iptables -A INPUT -p tcp --dport 548 -s 192.0.2.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 548 -j DROP

# Stop and disable Netatalk if not required
systemctl stop netatalk
systemctl disable netatalk