CVE-2024-50400 Overview
CVE-2024-50400 is a use of externally-controlled format string vulnerability [CWE-134] affecting multiple versions of QNAP's QTS and QuTS hero network-attached storage (NAS) operating systems. Remote attackers who have already obtained administrator access can exploit the flaw to read secret data from process memory or modify memory contents. QNAP addressed the issue in QTS 5.2.1.2930 build 20241025 and QuTS hero h5.2.1.2929 build 20241025.
Critical Impact
Authenticated administrators on affected QNAP NAS appliances can leak sensitive memory contents or corrupt memory through crafted format string input, undermining confidentiality and integrity of the storage OS.
Affected Products
- QNAP QTS versions from 5.2.0.2737 through 5.2.0.2860 (prior to 5.2.1.2930 build 20241025)
- QNAP QuTS hero versions from h5.2.0.2737 through h5.2.0.2860 (prior to h5.2.1.2929 build 20241025)
- NAS appliances running the impacted QTS and QuTS hero builds listed in QNAP Security Advisory QSA-24-43
Discovery Timeline
- 2024-11-22 - CVE-2024-50400 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-50400
Vulnerability Analysis
The flaw is a classic externally-controlled format string weakness. Attacker-supplied input reaches a formatted output function without a fixed format specifier. That input is then interpreted as format directives such as %x, %s, or %n. Reading directives disclose stack or heap contents, while writing directives can modify arbitrary memory locations reachable through the argument list.
Exploitation on QTS and QuTS hero requires prior administrator authentication over the network. The attack complexity is high because reliable exploitation depends on process layout and reachable pointers. Successful exploitation compromises confidentiality and integrity of the NAS operating system itself, not just the exposed application surface.
Root Cause
The root cause is missing sanitization of an externally supplied string that is passed to a formatting API as the format argument. Any function in the printf family, or a wrapper that forwards user data into such a call, treats the string as a template. QNAP's fix in QTS 5.2.1.2930 and QuTS hero h5.2.1.2929 removes the tainted path, most likely by enforcing a fixed format string and passing user data only as an argument.
Attack Vector
The attack is network-reachable but gated by administrator privileges (PR:H). An authenticated administrator sends a crafted request containing format specifiers to the vulnerable component. Because administrator credentials are required, the practical threat model centers on credential theft, insider misuse, session hijacking, and post-exploitation escalation from other flaws. No public proof-of-concept or in-the-wild exploitation has been reported for this CVE.
No verified exploit code is publicly available for CVE-2024-50400. Refer to QNAP Security Advisory QSA-24-43 for authoritative technical details.
Detection Methods for CVE-2024-50400
Indicators of Compromise
- Presence of format specifier sequences such as %x, %s, %n, or %p inside HTTP request parameters, headers, or POST bodies directed at NAS management endpoints.
- Unexpected process crashes, segmentation faults, or restarts logged in QTS or QuTS hero system logs during or after administrator sessions.
- Administrator logins originating from unfamiliar IP addresses or during unusual hours, followed by non-standard API activity.
Detection Strategies
- Inspect NAS management traffic and web logs for request parameters containing repeated % tokens that match printf-family format specifiers.
- Correlate administrator authentication events with subsequent abnormal process behavior on the NAS, including memory access errors.
- Baseline routine administrator API usage and alert on deviations that involve raw string input to configuration endpoints.
Monitoring Recommendations
- Forward QTS and QuTS hero syslog and audit events to a centralized log platform for retention and analysis.
- Monitor administrator account creation, privilege changes, and remote sessions on all NAS appliances.
- Track firmware version inventory across QNAP devices to identify appliances still exposed to CVE-2024-50400.
How to Mitigate CVE-2024-50400
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, following the guidance in QNAP Security Advisory QSA-24-43.
- Rotate administrator credentials and audit all accounts with administrative roles on affected NAS appliances.
- Remove direct exposure of the NAS management interface from the public internet.
Patch Information
QNAP has released fixed firmware in QTS 5.2.1.2930 build 20241025 and QuTS hero h5.2.1.2929 build 20241025. Apply updates through the QTS/QuTS hero web interface under Control Panel > System > Firmware Update, or download the images from the QNAP support portal. Confirm the running build number after the update completes.
Workarounds
- Restrict access to NAS administration endpoints to a management VLAN or trusted IP allowlist until firmware can be updated.
- Enforce multi-factor authentication and strong passwords on all administrator accounts to raise the bar for the required privilege precondition.
- Disable unused administrative services and reduce the number of accounts holding administrator role assignments.
# Verify the running QTS/QuTS hero build after patching
# From the NAS SSH console:
getcfg System Version
getcfg System "Build Number"
# Expected minimum values:
# QTS >= 5.2.1.2930 build 20241025
# QuTS hero >= h5.2.1.2929 build 20241025
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
