Today, in coordination with Ilya Lipnitskiy (the maintainer of libcue) and the distros mailing list, the GitHub Security Lab is disclosing CVE-2023-43641, a memory corruption vulnerability in libcue. We have also sent a text-only version of this blog post to the oss-security list.
libcue is a library used for parsing cue sheets—a metadata format for describing the layout of the tracks on a CD. Cue sheets are often used in combination with the FLAC audio file format, which means that libcue is a dependency of some audio players, such as Audacious. But the reason why I decided to audit libcue for security vulnerabilities is that it’s used by tracker-miners: an application that’s included with GNOME—the default graphical desktop environment of many open source operating systems. The purpose of tracker-miners is to index the files in your home directory to make them easily searchable.
To make a long story short, that means that inadvertently clicking a malicious link is all it takes for an attacker to exploit CVE-2023-43641 and get code execution on your computer.
The offsets in the full PoC need to be tuned for different distributions. I have only done this for Ubuntu 23.04 and Fedora 38, the most recent releases of Ubuntu and Fedora at this time. In my testing, I have found that the PoC works very reliably when run on the correct distribution (and will trigger a SIGSEGV when run on the wrong distribution). I have not created PoCs for any other distributions, but I believe that all distributions that run GNOME are potentially exploitable.
Sometimes a vulnerability in a seemingly innocuous library can have a large impact. Due to the way that it’s used by tracker-miners, this vulnerability in libcue became a 1-click RCE. If you use GNOME, please update today!