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

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-11 · updated 2026-06-17
• Weakness: CWE-125

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.

Affected products

• vim/vim: before 9.2.0565 — fixed in 9.2.0565

How to fix

Upgrade to a fixed version: vim/vim 9.2.0565. Check the vendor advisory for mitigations.

References

• https://github.com/vim/vim/commit/63680c6d3d52477817b49cd1a66e7aabe8a7aa19
• https://github.com/vim/vim/releases/tag/v9.2.0565
• https://github.com/vim/vim/security/advisories/GHSA-47gw-8gc3-mgcm

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