Cyber Resilience

CVE-2023-34966

DoS in Samba ≤ 4.16.11

High EPSSDoS
Published
20 July 2023
Modified
21 November 2024
Patch / advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.62 99.1th percentile
Risk Priority 81 floored blend · peak EPSS

Summary

CVE-2023-34966 is a high-severity Infinite Loop (CWE-835) vulnerability in Samba Samba. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 0.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-34966 is an infinite loop vulnerability in Samba's mdssvc RPC service used for Spotlight indexing. The flaw resides in the core unmarshalling function sl_unpack_loop(), which fails to validate a client-supplied count field for an array-like structure in incoming Spotlight mdssvc RPC packets; supplying a value of zero causes the function to loop indefinitely and consume 100% CPU. The affected component is the Samba server implementation of the mdssvc protocol.

An unauthenticated remote attacker can exploit the issue by sending a single malformed RPC request over the network. Because the CVSS vector indicates no privileges or user interaction are required, the attack results in a denial-of-service condition that renders the Samba service unresponsive while the CPU remains saturated.

Red Hat has published multiple errata (RHSA-2023:6667, RHSA-2023:7139, RHSA-2024:0423, RHSA-2024:0580, and RHSA-2024:4101) that deliver patched Samba packages addressing the vulnerability.

The EPSS score has remained in the 0.14–0.16 range since disclosure, indicating moderate but not sharply increasing exploitation interest.

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-34967Same product: Debian Debian Linux
CVE-2023-3255Same product: Fedoraproject Fedora
CVE-2023-34968Same product: Debian Debian Linux
CVE-2023-2602Same product: Debian Debian Linux
CVE-2023-2156Same product: Debian Debian Linux
CVE-2023-2952Same product: Debian Debian Linux
CVE-2025-38727Same product: Debian Debian Linux
CVE-2024-4854Same product: Fedoraproject Fedora
CVE-2025-38001Same product: Debian Debian Linux
CVE-2025-38588Same product: Debian Debian Linux

Affected Assets

samba
samba
≤ 4.16.11 · 4.17.0 — 4.17.10 · 4.18.0 — 4.18.5
fedoraproject
fedora
37, 38
redhat
enterprise linux
8.0, 9.0
debian
debian linux
11.0, 12.0

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-835

Enables transfer to alternate site if an infinite loop at the primary renders processing unavailable.

addresses: CWE-835

Detects and mitigates infinite loops that produce sustained resource consumption.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (reviews, testing, static analysis) directly prevent introduction of infinite-loop defects.

ID.RA-01 partial match
prevents

Static analysis and vuln scanning during asset assessment can detect unreachable loop exits.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Security testing can uncover infinite-loop conditions before release.

prevents

Secure development life cycle mandates practices that can detect and prevent infinite-loop defects.

prevents

Application security requirements can specify loop-termination rules, indirectly reducing the weakness.

prevents

Secure coding standards directly address loop termination and prevent infinite loops.

none

Secure architecture principles encourage designs that avoid unreachable exit conditions.

none

Change management can require review of loop logic when code is modified.

References