A flaw was found in dbus when configured with the nonce-tcp transport. An unauthenticated attacker able to connect to an exposed listener can cause a Denial of Service (DoS) by opening a connection and withholding the expected authentication token. Because the server processes this verification without enforcing a timeout, the stalled connection blocks the accept process and prevents legitimate clients from establishing new connections.

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Fixes

Solution

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Workaround

Disable non-standard `nonce-tcp` listeners in the D-Bus configuration in favor of standard UNIX domain sockets. If network reachability is required, restrict access to trusted hosts using `firewalld`. To remove an exposed port from an untrusted firewall zone: ``` firewall-cmd --permanent --zone=public --remove-port=<PORT>/tcp firewall-cmd --permanent --zone=trusted --add-source=<TRUSTED_IP_OR_SUBNET> firewall-cmd --reload ``` Caveats: Restricting or disabling network listeners prevents remote clients outside the trusted subnet from connecting to the affected bus. Warning: Reloading the firewall rules or altering the D-Bus server configuration requires restarting the affected D-Bus service, which will drop existing connections and temporarily disrupt communications.

History

Fri, 13 Nov 2026 21:45:00 +0000

Type Values Removed Values Added
Description A flaw was found in dbus when configured with the nonce-tcp transport. An unauthenticated attacker able to connect to an exposed listener can cause a Denial of Service (DoS) by opening a connection and withholding the expected authentication token. Because the server processes this verification without enforcing a timeout, the stalled connection blocks the accept process and prevents legitimate clients from establishing new connections.
Title Dbus: server accept watch can be stalled by blocking nonce-tcp accept_with_noncefile path
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-1322
CPEs cpe:/a:redhat:enterprise_linux:10
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-11-13T21:42:20.482Z

Reserved: 2026-11-13T11:51:37.809Z

Link: CVE-2026-128886

cve-icon Vulnrichment

No data.

cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses