CVE-2026-52859

Name	CVE-2026-52859
Description	Vim is an open source, command line text editor. Prior to version 9.2.0565, the update_snapshot() function in src/terminal.c copies the visible terminal screen into the scrollback buffer when a snapshot is taken. For each screen cell it walks the cell's chars[] array with no upper bound, stopping only when it encounters a NUL terminator. When a cell legitimately fills all VTERM_MAX_CHARS_PER_CELL (6) slots — a base character plus five combining marks — the bundled libvterm returns the array without a terminating NUL, so the loop reads past the fixed six-element array and appends the out-of-bounds values to a buffer reserved for only six characters. A program whose output is rendered inside a :terminal window can trigger this with a short byte sequence and no Vim scripting, leading to a crash. This issue has been patched in version 9.2.0565.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1139729

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
vim (PTS)	bullseye	2:8.2.2434-3+deb11u1	vulnerable
	bullseye (security)	2:8.2.2434-3+deb11u3	vulnerable
	bookworm	2:9.0.1378-2+deb12u2	vulnerable
	trixie	2:9.1.1230-2	vulnerable
	forky, sid	2:9.2.0524-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
vim	source	(unstable)	(unfixed)	unimportant		1139729

Notes

https://github.com/vim/vim/security/advisories/GHSA-47gw-8gc3-mgcm
Fixed by: https://github.com/vim/vim/commit/63680c6d3d52477817b49cd1a66e7aabe8a7aa19 (v9.2.0565)
Crash in CLI tool, no security impact