CVE-2026-44061: Netatalk Timing Side Channel Vulnerability

CVE-2026-44061 Overview

CVE-2026-44061 is a timing side-channel vulnerability in Netatalk, an open-source implementation of the Apple Filing Protocol (AFP) used to provide file services to macOS clients on Linux and BSD systems. Versions 1.5.0 through 4.4.2 use Data Encryption Standard in Electronic Codebook mode (DES-ECB) for authentication. The implementation leaks timing information during credential verification. A remote attacker can analyze these timing variations to recover authentication credentials over the network. The flaw is classified under [CWE-208] Observable Timing Discrepancy.

Critical Impact
Remote attackers can recover Netatalk authentication credentials through statistical timing analysis, exposing file shares to unauthorized access.

Affected Products

Netatalk 1.5.0 through 4.4.2
Linux and BSD distributions packaging vulnerable Netatalk releases
Network-attached storage appliances bundling Netatalk for AFP services

Discovery Timeline

2026-05-21 - CVE-2026-44061 published to NVD
2026-05-21 - Last updated in NVD database

Technical Details for CVE-2026-44061

Vulnerability Analysis

Netatalk's authentication path relies on DES-ECB to validate client credentials during AFP session establishment. The cryptographic comparison and decryption operations execute in time intervals that correlate with the secret key material being processed. An attacker who can issue repeated authentication attempts and measure response latency precisely can build a statistical model of the credential bytes. Over enough samples, the timing distribution reveals the secret used to authenticate AFP clients.

DES itself is considered cryptographically obsolete due to its 56-bit effective key length. Pairing DES with ECB mode compounds the weakness, since identical plaintext blocks produce identical ciphertext blocks. The timing channel transforms this design weakness into a practical credential recovery primitive reachable over the network.

Root Cause

The root cause is non-constant-time handling of cryptographic operations and credential comparisons in the authentication routine. Implementations that branch or short-circuit based on secret-dependent values emit observable timing differences. Netatalk's continued use of DES-ECB for authentication, rather than a modern authenticated key exchange, leaves the protocol exposed to side-channel analysis even when network traffic is otherwise unmodified.

Attack Vector

Exploitation requires network reachability to the AFP service, typically TCP port 548. The attacker repeatedly initiates authentication exchanges and records server response times with high precision. Statistical analysis of the timing data progressively narrows the key space. No user interaction or prior authentication is required, though high attack complexity reflects the need for stable network conditions and large sample sizes. Refer to the Netatalk Security Advisory for protocol-level technical details.

Detection Methods for CVE-2026-44061

Indicators of Compromise

High volumes of AFP authentication attempts from a single source IP against TCP port 548
Repeated short-lived AFP sessions terminating immediately after the authentication phase
Successful AFP logins from previously unseen geographies or networks following sustained probing

Detection Strategies

Monitor afpd and Netatalk logs for abnormal rates of authentication failures and reconnection patterns
Deploy network intrusion detection signatures for repeated AFP FPLogin requests from individual hosts
Correlate AFP authentication telemetry with endpoint identification of credential-stuffing tooling

Monitoring Recommendations

Enable verbose logging in Netatalk and forward events to a centralized SIEM for baseline analysis
Alert on AFP session establishment originating from outside trusted client subnets
Track latency-sensitive scanning behavior such as uniform request intervals targeting port 548

How to Mitigate CVE-2026-44061

Immediate Actions Required

Upgrade Netatalk to a fixed release published after version 4.4.2 once available from the maintainers
Restrict AFP service exposure to trusted management networks using host or network firewalls
Disable AFP entirely where SMB or other modern protocols can serve the same clients

Patch Information

Consult the Netatalk Security Advisory for fixed version numbers, patch commits, and upgrade guidance. Distribution maintainers typically backport fixes to packaged releases, so apply vendor updates as they become available.

Workarounds

Block inbound TCP port 548 at perimeter and segmentation firewalls when external AFP access is not required
Place AFP services behind a VPN to prevent untrusted clients from initiating authentication attempts
Rotate AFP credentials and enforce strong, unique passwords to increase the cost of timing-based recovery

bash

# Configuration example: restrict AFP access with iptables
iptables -A INPUT -p tcp --dport 548 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 548 -j DROP