CVE-2024-50396 Overview
CVE-2024-50396 is an externally-controlled format string vulnerability [CWE-134] affecting multiple versions of QNAP QTS and QuTS hero operating systems. Remote attackers can exploit this flaw to read secret data from memory or modify memory contents on affected network-attached storage (NAS) devices. QNAP disclosed the issue in security advisory QSA-24-43 and released fixes in QTS 5.2.1.2930 build 20241025 and QuTS hero h5.2.1.2929 build 20241025. The vulnerability carries a CVSS 4.0 base score of 7.7 and requires limited user interaction over the network.
Critical Impact
Successful exploitation enables remote attackers to disclose sensitive memory contents or modify process memory on QNAP NAS devices, undermining confidentiality, integrity, and availability of stored data.
Affected Products
- QNAP QTS 5.2.x prior to 5.2.1.2930 build 20241025
- QNAP QuTS hero h5.2.x prior to h5.2.1.2929 build 20241025
- QNAP NAS appliances running the affected QTS and QuTS hero builds listed in CPE data
Discovery Timeline
- 2024-11-22 - CVE-2024-50396 published to the National Vulnerability Database
- 2025-09-23 - Last updated in NVD database
Technical Details for CVE-2024-50396
Vulnerability Analysis
The flaw is classified under [CWE-134] Use of Externally-Controlled Format String. The affected QTS and QuTS hero components pass attacker-controllable input directly into a format string parameter of a formatted output function. When the function processes specifiers such as %x, %s, or %n supplied by the attacker, the underlying routine reads from or writes to memory locations that the application never intended to expose.
Attackers can leverage this primitive to leak stack contents, heap pointers, or secrets resident in process memory. They can also use write specifiers to corrupt memory and influence program control flow. QNAP confirmed both information disclosure and memory modification outcomes in advisory QSA-24-43.
Root Cause
The root cause is the absence of a fixed format string literal in calls to formatted output APIs within QTS and QuTS hero services. User-supplied data is concatenated into or substituted for the format argument, allowing the attacker to inject conversion specifiers. Proper coding practice requires passing untrusted input as a variadic argument while keeping the format string as a constant.
Attack Vector
The attack vector is network-based and requires passive user interaction, consistent with the CVSS 4.0 vector. A remote attacker delivers crafted input to an exposed QTS or QuTS hero service that ultimately reaches the vulnerable format function. No prior authentication is required. Successful exploitation impacts confidentiality, integrity, and availability of the affected NAS host. No public proof-of-concept exploit, ExploitDB entry, or CISA KEV listing exists for CVE-2024-50396 at the time of writing. The EPSS probability is 1.577% (81.87 percentile).
No verified public exploit code is available. See the QNAP Security Advisory QSA-24-43 for vendor technical details.
Detection Methods for CVE-2024-50396
Indicators of Compromise
- Unexpected crashes, restarts, or segmentation faults in QTS or QuTS hero system services
- Inbound HTTP or management-plane requests containing format specifier sequences such as %s, %x, %n, or long %p chains targeting NAS web interfaces
- Anomalous outbound connections originating from QNAP NAS appliances following suspicious management requests
Detection Strategies
- Inspect QNAP system logs (/var/log) and web-access logs for malformed parameters containing format conversion specifiers
- Compare installed firmware versions against fixed builds QTS 5.2.1.2930 and QuTS hero h5.2.1.2929; any earlier 5.2.x build is exposed
- Deploy network IDS signatures that flag HTTP request parameters containing repeated format specifier patterns targeting QNAP management ports
Monitoring Recommendations
- Monitor QNAP appliance authentication, configuration, and process-crash events and forward them to a central SIEM for correlation
- Track north-south traffic to QNAP management interfaces (typically TCP 8080, 443, 8443) and alert on requests originating from untrusted networks
- Establish a baseline of normal administrative activity and alert on deviations such as new admin sessions or unexpected service restarts
How to Mitigate CVE-2024-50396
Immediate Actions Required
- Upgrade QTS to 5.2.1.2930 build 20241025 or later, and QuTS hero to h5.2.1.2929 build 20241025 or later, per QNAP advisory QSA-24-43
- Remove direct internet exposure of NAS management interfaces and restrict access to trusted management networks or VPN
- Audit administrator accounts, rotate credentials, and enable multi-factor authentication on all QNAP management accounts
Patch Information
QNAP fixed the vulnerability in QTS 5.2.1.2930 build 20241025 and QuTS hero h5.2.1.2929 build 20241025. Apply updates through the QTS or QuTS hero Control Panel under System > Firmware Update > Live Update, or download the firmware directly from the QNAP support portal. Refer to the QNAP Security Advisory QSA-24-43 for complete patch guidance.
Workarounds
- Place QNAP NAS devices behind a firewall and block external access to the management web interface until firmware is updated
- Disable unused services and protocols on the NAS to reduce the reachable attack surface
- Enforce IP allowlisting and rate limiting on management endpoints to limit unauthenticated access attempts
# Verify installed QTS or QuTS hero version via SSH
getcfg System Version
getcfg System "Build Number"
# Expected fixed builds:
# QTS: 5.2.1.2930 build 20241025 or later
# QuTS hero: h5.2.1.2929 build 20241025 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
