CVE-2026-45699 Netatalk has Integer Underflow → Stack Buffer Overflow in copydir()
An integer underflow in Netatalk's afpd daemon allows stack buffer overflows, potentially enabling remote code execution when file operations cross device boundaries.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45699?
CVE-2026-45699 is a high-severity vulnerability in netatalk, published on 14 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-191
Which versions are affected by CVE-2026-45699?
How do I fix CVE-2026-45699?
Apply the vendor's patch.
Is CVE-2026-45699 being exploited?
There is no known exploitation of CVE-2026-45699 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-45699, GHSA-fphv-pf29-p77m, UBUNTU-CVE-2026-45699.