CVE-2026-52859 Vim: Out-of-bounds Read in Terminal Screen Snapshot

Medium 6.9 Published 11 Jun 2026 Updated 11 Jun 2026

An out-of-bounds read in Vim's terminal snapshot function allows a crash when rendering specific combining characters in a terminal window.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-52859?

CVE-2026-52859 is a medium-severity memory corruption vulnerability in Vim Vim, published on 11 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-125

Which versions are affected by CVE-2026-52859?

It affects 1 product.

Products include Vim Vim.

How do I fix CVE-2026-52859?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-52859 being exploited?

There is no known exploitation of CVE-2026-52859 in the wild and no public exploit code.

All Vim Vim vulnerabilities

Sources

Also known as ALPINE-CVE-2026-52859, AZL-89772, BELL-CVE-2026-52859, CLSA-2026-1782143534, CLSA-2026-1782143913, CLSA-2026-1782143942 and 5 more.