Executive brief
Netatalk is an open-source implementation of the Apple Filing Protocol (AFP) used to allow Unix-like systems to serve as file servers for macOS clients. A security flaw in an older authentication method could allow an attacker to potentially discover user credentials by measuring the time it takes for the server to respond to login attempts. While this specific authentication method is not enabled by default, an exploit could lead to unauthorized access to files and sensitive data stored on the server.
Technical details
A timing side-channel vulnerability (CWE-208) exists in the Randnum User Authentication Method (UAM) of Netatalk versions 1.5.0 through 4.4.2. The root cause is the use of DES in ECB mode combined with a non-constant-time comparison of authentication data. A remote, unauthenticated attacker can exploit this by measuring response times to differentiate between correct and incorrect authentication fragments, potentially leading to credential recovery. The attack complexity is high as it requires precise timing measurements and the Randnum UAM must be manually enabled. The issue is resolved in Netatalk version 4.5.0.
Affected products
- Netatalk team Netatalk 1.5.0 through 4.4.2
Timeline
- 2026-05-13: disclosed
- 2026-05-21: advisory: NVD publication date
- 2026-05-21: patched: Fixed in version 4.5.0