segmentation fault in win_line() in Vim < 9.1.1043

Vulnerability Description

Vim is an open source, command line text editor. A segmentation fault was found in Vim before 9.1.1043. In silent Ex mode (-s -e), Vim typically doesn't show a screen and just operates silently in batch mode. However, it is still possible to trigger the function that handles the scrolling of a gui version of Vim by feeding some binary characters to Vim. The function that handles the scrolling however may be triggering a redraw, which will access the ScreenLines pointer, even so this variable hasn't been allocated (since there is no screen). This vulnerability is fixed in 9.1.1043.

References

• https://github.com/vim/vim/security/advisories/GHSA-j3g9-wg22-v955
• https://github.com/vim/vim/commit/9d1bed5eccdbb46a26b8a484f5e9163c40e63919