---
id: "CVE-2026-106971"
kind: "vulnerability"
aliases: ["CVE-2026-106971"]
title: "rybakit/msgpack: integer overflow in BufferUnpacker enables denial of service"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["api-servers", "composer", "package", "php", "rybakit-msgpack"]
not_affected_if: ["not-using-v0.11.0", "trusted-input-only"]
published_at: "2026-10-28T15:17:02+00:00"
first_seen_at: "2026-10-28T15:33:37+00:00"
updated_at: "2026-10-28T15:35:09+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106971", "first_seen_at": "2026-10-28T15:33:37+00:00"}]
---

# rybakit/msgpack: integer overflow in BufferUnpacker enables denial of service

The MessagePack\BufferUnpacker component of the rybakit/msgpack PHP library v0.11.0 has an integer overflow. A crafted input can make the process crash or hang, causing denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version with `composer show rybakit/msgpack`
- Look for `rybakit/msgpack` in `composer.lock` and confirm whether it resolves to `0.11.0`
- Check whether the application unpacks untrusted MessagePack input with `BufferUnpacker`

## Fix

- Upgrade `rybakit/msgpack` past `0.11.0` to a patched release (the fixed version is unknown from the sources)
- Until patched, reject or size-limit untrusted MessagePack payloads before unpacking

## Timeline

- 2026-10-28T15:33:37+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-106971

## From the sources

An integer overflow in the MessagePack\BufferUnpacker component of rybakit/msgpack v0.11.0 allows attackers to cause a Denial of Service (DoS) via a crafted input.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_