CVE-2023-34966 Samba: infinite loop in mdssvc rpc service for spotlight

High 7.5 Published 20 Jul 2023 Updated 20 Nov 2025

An attacker can cause a denial of service in Samba's mdssvc RPC service by sending a malformed packet with a zero element count, triggering an infinite loop.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2023-34966?

CVE-2023-34966 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 20 Jul 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An infinite loop vulnerability was found in Samba's mdssvc RPC service for Spotlight. When parsing Spotlight mdssvc RPC packets sent by the client, the core unmarshalling function sl_unpack_loop() did not validate a field in the network packet that contains the count of elements in an array-like structure. By passing 0 as the count value, the attacked function will run in an endless loop consuming 100% CPU. This flaw allows an attacker to issue a malformed RPC request, triggering an infinite loop, resulting in a denial of service condition.

Weakness: CWE-835

Which versions are affected by CVE-2023-34966?

It affects 4 products.

Linux distribution packages (40)

`ctdb-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`libnetapi-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`libsmbclient-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`libwbclient-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`python3-samba-dc-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`python3-samba-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-client` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-client-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-client-libs-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-common-libs-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-common-tools-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-dc-libs-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-dcerpc-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-debugsource` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-krb5-printing` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-krb5-printing-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-ldb-ldap-modules-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-libs-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-test-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-test-libs-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-vfs-iouring` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-vfs-iouring-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winbind-clients` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winbind-clients-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winbind-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winbind-krb5-locator` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winbind-krb5-locator-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winbind-modules-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winexe` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`samba-winexe-debuginfo` Red Hat:rhel_eus:9.2::appstream	All versions	`0:4.17.5-105.el9_2`
`ctdb-debuginfo` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`libnetapi` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`libnetapi-debuginfo` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`libsmbclient` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`libsmbclient-debuginfo` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`libwbclient` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`libwbclient-debuginfo` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`python3-samba` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`
`python3-samba-dc` Red Hat:rhel_eus:9.2::baseos	All versions	`0:4.17.5-105.el9_2`

Products include Debian Debian Linux, Fedoraproject Fedora, Redhat Enterprise Linux, Samba Samba.

How do I fix CVE-2023-34966?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-34966 being exploited?

There is no known exploitation of CVE-2023-34966 in the wild and no public exploit code.

All Debian Debian Linux vulnerabilities

Sources

Also known as AZL-27661, AZL-37021, CLSA-2023-1691576181, CLSA-2023-1691576572, CLSA-2024-1724260726, DEBIAN-CVE-2023-34966 and 4 more.