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

> An attacker can trigger heap buffer over-read/write in Kitty terminal via integer overflow in graphics composition, potentially leading to code execution.

- **Severity:** Critical 9.9 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 May 2026
- **Updated:** 19 May 2026
- **Also known as:** DEBIAN-CVE-2026-33642, GHSA-qfgm-2c64-6x3x, UBUNTU-CVE-2026-33642

## What is CVE-2026-33642?

CVE-2026-33642 is a critical vulnerability in kovidgoyal kitty, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-787 (Out-of-bounds Write), CWE-190 (Integer Overflow or Wraparound), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-33642?

It affects 1 product.


Products: Kovidgoyal Kitty.

## How do I fix CVE-2026-33642?

Upgrade to a fixed version.

## Is CVE-2026-33642 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33642 exists.

## Other vulnerabilities in kovidgoyal kitty

- [CVE-2026-42851](https://insights.sbomify.com/CVE-2026-42851/): @kitty-edit DCS + --color=geninclude vulnerable to Unauthenticated in-process RCE (high 7.8)
- [CVE-2026-54056](https://insights.sbomify.com/CVE-2026-54056/): Kitty has an arbitrary file overwrite via symlink following in `kitten dnd` remote drop staging (high 7.6)
- [CVE-2026-33633](https://insights.sbomify.com/CVE-2026-33633/): Kitty has a Heap Buffer Overflow in its Graphics Protocol Handler (high 7.5)
- [CVE-2026-42850](https://insights.sbomify.com/CVE-2026-42850/): Kitty has a shell command injection (high 7.4)
- [CVE-2026-54057](https://insights.sbomify.com/CVE-2026-54057/): Kitty vulnerable to command injection via unsanitized OSC 21 query reply (high 7.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33642 and fix it if it is affected.

What it is: CVE-2026-33642 is a critical vulnerability in kovidgoyal kitty, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33642 exists.

Affected product: kovidgoyal kitty. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-33642/ (Markdown: https://insights.sbomify.com/CVE-2026-33642/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33642
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33642
- OSV: https://osv.dev/vulnerability/CVE-2026-33642

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33642/
Summaries are generated and may contain mistakes; the official description above is the record.