---
id: "CVE-2026-120749"
page: "https://infrastack.ai/live/CVE-2026-120749"
kind: "vulnerability"
aliases: ["CVE-2026-120749"]
title: "D-Bus: a local user can crash the bus daemon via monitoring"
severity: "medium"
cvss: 6.2
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["dbus", "infrastructure", "linux", "self-hosted", "system-bus"]
not_affected_if: ["no-monitoring-client-attached"]
published_at: "2026-11-06T07:17:06+00:00"
first_seen_at: "2026-11-06T07:40:16+00:00"
updated_at: "2026-11-06T07:41:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120749", "first_seen_at": "2026-11-06T07:40:16+00:00"}]
exploit_sources: []
---

# D-Bus: a local user can crash the bus daemon via monitoring

Link for people: https://infrastack.ai/live/CVE-2026-120749 (this .md is for agents)

When a privileged monitoring client such as dbus-monitor is attached, a local unprivileged user can make dbus-daemon abort by triggering a failed delivery of a driver broadcast. On the system bus this results in a denial of service.

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

## How to check

- `dbus-daemon --version` to see the installed D-Bus version
- Check whether monitoring clients such as `dbus-monitor` or `busctl monitor` are attached on systems where the system bus is used
- Fix versions: unknown

## Timeline

- 2026-11-06T07:40:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120749

## From the sources

A flaw was found in D-Bus. With a privileged Monitoring client attached (for example dbus-monitor or busctl monitor), an unprivileged local user can cause dbus-daemon to abort if a driver-originated broadcast such as NameOwnerChanged or ActivatableServicesChanged cannot be delivered to a recipient (for example due to a deny rule or an exceeded outgoing message queue). Driver broadcasts still use serial 0; when delivery fails, composing the monitor error reply asserts reply_serial != 0 and aborts the daemon. This is an incomplete fix for CVE-2023-34969, which only assigned serials for driver messages sent to a single recipient. On the well-known system bus this is a denial of service.

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