Dbus: server accept watch can be stalled by blocking nonce-tcp accept_with_noncefile path
Summary
| CVE | CVE-2026-128886 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-13 22:17:23 UTC |
| Updated | 2026-11-13 22:17:23 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 6.2 MEDIUM from [email protected]
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Problem Types: CWE-1322 | CWE-1322 Use of Blocking Code in Single-threaded, Non-blocking Context
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 6.2 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 6.2 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-128886 | [email protected] | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-05-11T20:27:44.000Z | Reported to Red Hat. |
| CNA | 2026-08-19T16:20:17.572Z | Made public. |
Workarounds
CNA: 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.