What’s Vulnerable › Vulnerabilities

CVE-2023-42669: Samba: "rpcecho" development server allows denial of service via sleep() call on ad dc

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-11-06 · updated 2026-06-17
• Weakness: CWE-400

Description

A vulnerability was found in Samba's "rpcecho" development server, a non-Windows RPC server used to test Samba's DCE/RPC stack elements. This vulnerability stems from an RPC function that can be blocked indefinitely. The issue arises because the "rpcecho" service operates with only one worker in the main RPC task, allowing calls to the "rpcecho" server to be blocked for a specified time, causing service disruptions. This disruption is triggered by a "sleep()" call in the "dcesrv_echo_TestSleep()" function under specific conditions. Authenticated users or attackers can exploit this vulnerability to make calls to the "rpcecho" server, requesting it to block for a specified duration, effectively disrupting most services and leading to a complete denial of service on the AD DC. The DoS affects all other services as "rpcecho" runs in the main RPC task.

Affected products

• Red Hat Enterprise Linux: 8.0, 9.0
• RedHat Enterprise Linux Eus: 9.0
• RedHat Enterprise Linux For Ibm Z Systems: 9.0_s390x
• RedHat Enterprise Linux For Ibm Z Systems Eus: 9.0_s390x
• RedHat Enterprise Linux For Power Little Endian: 9.0_ppc64le
• RedHat Enterprise Linux For Power Little Endian Eus: 9.0_ppc64le
• RedHat Storage: 3.0
• Samba: from 4.0.0 before 4.17.12; from 4.18.0 before 4.18.8; from 4.19.0 before 4.19.1 — fixed in 4.17.12, 4.18.8, 4.19.1

How to fix

Upgrade to a fixed version: Samba 4.17.12, 4.18.8, 4.19.1. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2023:6209
• https://access.redhat.com/errata/RHSA-2023:6744
• https://access.redhat.com/errata/RHSA-2023:7371
• https://access.redhat.com/errata/RHSA-2023:7408
• https://access.redhat.com/errata/RHSA-2023:7464
• https://access.redhat.com/errata/RHSA-2023:7467
• https://access.redhat.com/security/cve/CVE-2023-42669
• https://bugzilla.redhat.com/show_bug.cgi?id=2241884
• https://bugzilla.samba.org/show_bug.cgi?id=15474
• https://www.samba.org/samba/security/CVE-2023-42669.html
• https://access.redhat.com/errata/RHSA-2023:6209
• https://access.redhat.com/errata/RHSA-2023:6744

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