CVE-2024-27127: QNAP QTS Use-After-Free Vulnerability

CVE-2024-27127 Overview

CVE-2024-27127 is a double free vulnerability [CWE-415] affecting several versions of QNAP QTS and QuTS hero operating systems. Authenticated users can exploit the flaw over a network to execute arbitrary code on affected network-attached storage (NAS) devices. QNAP disclosed the issue in security advisory QSA-24-23 and released fixes in QTS 5.1.7.2770 build 20240520 and QuTS hero h5.1.7.2770 build 20240520.

Critical Impact
Authenticated attackers can trigger memory corruption to achieve arbitrary code execution on the NAS, compromising the confidentiality, integrity, and availability of stored data.

Affected Products

QNAP QTS 5.1.x builds prior to 5.1.7.2770 build 20240520
QNAP QuTS hero h5.1.x builds prior to h5.1.7.2770 build 20240520
NAS appliances running the above vulnerable firmware versions

Discovery Timeline

2024-05-21 - CVE-2024-27127 published to NVD
2024-05-20 - QNAP releases patched builds (QTS 5.1.7.2770 and QuTS hero h5.1.7.2770)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-27127

Vulnerability Analysis

The flaw is a double free condition [CWE-415] in the QNAP QTS and QuTS hero operating systems. A double free occurs when the same memory region is released to the heap allocator twice, corrupting allocator metadata and creating conditions that attackers can leverage for arbitrary code execution.

Exploitation requires network access to the NAS management interface and valid low-privilege credentials. Once triggered, the memory corruption can be shaped into a write primitive that hijacks control flow within the affected service process. Successful exploitation grants execution in the context of the vulnerable service, exposing stored files, backups, and administrative credentials.

Root Cause

The root cause is improper management of heap-allocated memory within an affected QTS component. A code path frees a memory object and later frees the same pointer again without clearing or invalidating the reference. QNAP has not published the specific component or function affected in the public advisory.

Attack Vector

The attack is delivered over the network against the NAS. The attacker must authenticate first, then send crafted input to the vulnerable service to trigger the double free. QNAP has not released technical details, proof-of-concept code, or exploitation artifacts in the QSA-24-23 advisory.

No public exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the QNAP Security Advisory QSA-24-23 for vendor guidance.

Detection Methods for CVE-2024-27127

Indicators of Compromise

Unexpected crashes, restarts, or core dumps from QTS or QuTS hero service processes
New or unexpected administrator accounts, SSH keys, or scheduled tasks on the NAS
Outbound connections from the NAS to unknown external hosts following authenticated sessions

Detection Strategies

Audit QTS and QuTS hero system logs for authentication events followed by service errors or segmentation faults
Monitor for anomalous process execution or shell activity spawned by NAS management daemons
Correlate authenticated sessions from unusual source IP addresses with subsequent configuration changes

Monitoring Recommendations

Forward QNAP syslog output to a centralized SIEM for retention and correlation
Track firmware version inventory across all QNAP appliances to identify unpatched devices
Alert on privileged account creation, credential changes, and modifications to /etc/config on the NAS

How to Mitigate CVE-2024-27127

Immediate Actions Required

Upgrade QTS to 5.1.7.2770 build 20240520 or later
Upgrade QuTS hero to h5.1.7.2770 build 20240520 or later
Rotate all NAS user credentials, API tokens, and SSH keys after patching
Restrict NAS management interface exposure to trusted networks and VPN clients only

Patch Information

QNAP fixed the vulnerability in QTS 5.1.7.2770 build 20240520 and QuTS hero h5.1.7.2770 build 20240520. Administrators should apply the update through the QNAP QuLog Center or the Control Panel firmware update workflow. Full details are available in the QNAP Security Advisory QSA-24-23.

Workarounds

Disable remote access and myQNAPcloud services until the firmware update can be applied
Enforce strong, unique passwords and enable two-step verification for all NAS accounts
Place the NAS behind a firewall and block external access to management ports (8080, 443, 22)

bash

# Verify installed firmware version on QNAP NAS via SSH
getcfg System Version -f /etc/config/uLinux.conf
getcfg System "Build Number" -f /etc/config/uLinux.conf

# Restrict management access to a trusted subnet using QNAP firewall CLI
# Replace 10.0.0.0/24 with your management subnet
qfirewall -a -r "allow from 10.0.0.0/24 to any port 8080"
qfirewall -a -r "deny from any to any port 8080"