MesonLSP is an unofficial, unendorsed language server for meson written in C++. A vulnerability in versions prior to 4.1.4 allows overwriting arbitrary files if the attacker can make the victim either run the language server within a specific crafted project or `mesonlsp --full`. Version 4.1.4 contains a patch for this issue. As a workaround, avoid running `mesonlsp --full` and set the language server option `others.neverDownloadAutomatically` to `true`.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.