CVE-2026-57451: Vim: Out-of-bounds Read in Text Property Count

Vim is an open source, command line text editor. Prior to 9.2.0670, gettextprops() in src/textprop.c reads a uint16 property count stored inline after a line's text and returns it as the number of 32-byte textpropT entries that follow. The only check is a floor that guarantees room for a single entry; the count is never checked against the amount of data actually present. A line that declares a large count while carrying little data causes consumers to read far past the end of the line buffer. Such a line can be delivered through a crafted undo file, leading to a crash. This vulnerability is fixed in 9.2.0670.