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

> 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Jul 2023
- **Updated:** 20 Nov 2025
- **Also known as:** AZL-27661, AZL-37021, CLSA-2023-1691576181, CLSA-2023-1691576572, CLSA-2024-1724260726, DEBIAN-CVE-2023-34966, ECHO-5d53-654c-e8e2, GHSA-45c7-642q-qm9m, RHSA-2024:4101, UBUNTU-CVE-2023-34966

## 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 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2023-34966?

It affects 4 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `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: Debian Debian Linux, Fedoraproject Fedora, Redhat Enterprise Linux, Samba Samba.

## How do I fix CVE-2023-34966?

Apply the vendor's patch.

## Is CVE-2023-34966 being exploited?

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

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- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-34966 and fix it if it is affected.

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

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-34966/ (Markdown: https://insights.sbomify.com/CVE-2023-34966/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-34966
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-34966
- OSV: https://osv.dev/vulnerability/CVE-2023-34966

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-34966/
Summaries are generated and may contain mistakes; the official description above is the record.