CVE-2024-50398: QNAP QTS Format String Vulnerability

CVE-2024-50398 Overview

CVE-2024-50398 is a format string vulnerability affecting QNAP QTS and QuTS hero operating systems. The flaw allows remote attackers who have already obtained administrator access to read sensitive memory contents or modify memory on the affected device. QNAP disclosed the issue in security advisory QSA-24-43 and shipped fixes in QTS 5.2.1.2930 build 20241025 and QuTS hero h5.2.1.2929 build 20241025. The weakness is classified under CWE-134: Use of Externally-Controlled Format String.

Critical Impact
Authenticated administrators can leak secret data from process memory or corrupt memory contents on affected QNAP network-attached storage (NAS) appliances.

Affected Products

QNAP QTS versions prior to 5.2.1.2930 build 20241025
QNAP QuTS hero versions prior to h5.2.1.2929 build 20241025
Confirmed builds: QTS 5.2.0.2737 through 5.2.0.2860, and QuTS hero h5.2.0.2737 through h5.2.0.2860

Discovery Timeline

2024-11-22 - CVE-2024-50398 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-50398

Vulnerability Analysis

The vulnerability arises when QTS and QuTS hero pass attacker-influenced input directly to a format function such as printf, sprintf, or syslog without a fixed format specifier. When user-supplied data is interpreted as a format string, tokens such as %x, %s, and %n are processed by the format engine. This behavior lets an attacker walk the stack, disclose adjacent memory, or write to arbitrary addresses.

Exploitation requires prior administrator authentication on the NAS management interface. The attack is remote over the network, so any attacker who has phished, brute-forced, or otherwise acquired admin credentials can reach the vulnerable code paths.

Root Cause

The root cause is improper handling of externally-controlled input passed to a C-style format function. Instead of using a constant format string with separate arguments, the vulnerable routines allow user data to define the format itself, violating the guidance in CWE-134.

Attack Vector

An authenticated administrator submits crafted input containing format specifiers to a vulnerable QTS or QuTS hero component. The format function processes the specifiers, disclosing memory (using %x or %s) or writing memory (using %n). Refer to the QNAP Security Advisory QSA-24-43 for vendor-published details.

No public proof-of-concept exploit is available, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2024-50398

Indicators of Compromise

Administrator sessions submitting parameters containing format specifiers such as %s, %x, %n, or long %p sequences to QTS or QuTS hero endpoints.
Unexpected crashes, segmentation faults, or restarts of QNAP management services logged around the time of suspicious admin activity.
Administrator logins originating from unusual geolocations or IP addresses shortly before anomalous request patterns.

Detection Strategies

Inspect QTS and QuTS hero web management access logs for URL parameters or POST bodies that contain repeated % format tokens.
Correlate authenticated admin sessions with subsequent service errors in system logs to identify potential exploitation attempts.
Alert on any privileged account performing administrative actions from previously unseen source addresses.

Monitoring Recommendations

Forward QNAP system, event, and access logs to a centralized logging or SIEM platform for retention and analysis.
Enable multi-factor authentication (MFA) on all QNAP administrator accounts and monitor MFA failures.
Track firmware versions across the NAS fleet to ensure systems have moved to fixed builds.

How to Mitigate CVE-2024-50398

Immediate Actions Required

Upgrade QTS to 5.2.1.2930 build 20241025 or later.
Upgrade QuTS hero to h5.2.1.2929 build 20241025 or later.
Rotate administrator credentials and audit admin account membership on all QNAP appliances.
Restrict management interface access to trusted networks or VPN-only reachability.

Patch Information

QNAP addressed the vulnerability in QTS 5.2.1.2930 build 20241025 and QuTS hero h5.2.1.2929 build 20241025. Apply patches through the QNAP QuLog Center or Control Panel update mechanism. Full details are available in the QNAP Security Advisory QSA-24-43.

Workarounds

Remove NAS management interfaces from direct internet exposure and place them behind a VPN or reverse proxy with access controls.
Enforce strong, unique administrator passwords and enable two-step verification for all privileged accounts.
Limit the number of accounts assigned the administrator role and apply least-privilege principles for day-to-day operations.

bash

# Verify current QTS or QuTS hero firmware version via SSH
getcfg System Version
getcfg System "Build Number"

# Confirm the appliance is running a fixed build:
# QTS       >= 5.2.1.2930 build 20241025
# QuTS hero >= h5.2.1.2929 build 20241025