CVE-2026-33642 CRITICAL

CVE-2026-33642: Kitty has a Heap Buffer Over-Read/Write via Integer Overflow in compose_rectangles Bounds Check

Vendor Kovidgoyal
Product kitty
Weakness CWE-190
Published May 19, 2026
Last update May 19, 2026

CVSS base score

9.9/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H

What the vulnerability does

01Description

Kitty is a cross-platform GPU based terminal. In versions 0.46.2 and below, the handle_compose_command() function in kitty/graphics.c performs bounds validation on composition offsets using unsigned 32-bit arithmetic that is subject to integer wrapping, potentially leading to Heap Buffer Over-Read/Write. An attacker who can write escape sequences to a kitty terminal (e.g., via a malicious file, SSH login banner, or piped content) can supply crafted x_offset/y_offset values that pass the bounds check after wrapping but cause massive out-of-bounds heap memory access in compose_rectangles(). No user interaction is required. No non-default configuration is required. The attacker only needs the ability to produce output in a kitty terminal window. This issue has been fixed in version 0.47.0.

Key dates

02Disclosure timeline

May 19, 2026 CVE published
May 19, 2026 Record updated