Bug 2516136 (CVE-2026-45699)

Summary: CVE-2026-45699 netatalk: Netatalk: Stack-based buffer overflow in copydir() allows arbitrary code execution
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Netatalk. An integer underflow vulnerability exists in the `copydir()` function of the `afpd` daemon. This flaw occurs when a file operation crosses a device boundary within an Apple Filing Protocol (AFP) shared volume. Incorrect calculation of buffer size can lead to a stack-based buffer overflow, potentially allowing an attacker to achieve arbitrary code execution or cause a denial of service.
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Description OSIDB Bzimport 2026-08-14 19:32:38 UTC 
Netatalk is a Free and Open Source file server suite for Unix-like operating systems. In versions 3.1.19 through 4.4.2, a  stack-based buffer overflow exists in the copydir() function of Netatalk's afpd daemon due to an integer underflow in the calculation of the remaining buffer size used for path construction. copydir() is a utility function called when a file operation crosses a device boundary inside an AFP shared volume, which the standard library's renameat() cannot handle. The function attempts to track available buffer space using srem and drem for source and destination paths. Incorrect arithmetic causes both srem and drem to underflow to SIZE_MAX. Consequently, boundary checks against strlen(de->d_name) always pass, allowing strcpy() to append filenames into nearly full stack buffers. Version 4.4.3 patches the issue. As a workaround, configure each AFP shared volume to be structured as a single file system, in other words no subdirectory of a shared volume should be a mount point for a different file system.