Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain QNAP administrator account
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ExploitSend crafted request to QTS service
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ExecutionTrigger NULL pointer dereference (CWE-476)
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ImpactCrash service causing denial of service
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires the attacker to already possess a valid QNAP administrator account (CVSS PR:H), which is the dominant limiting factor - this is a post-authentication, privileged-user vulnerability, not a remotely exploitable unauthenticated flaw. Affected products are QTS 5.2.x builds prior to 5.2.6.3195 build 20250715 (per the CPE list spanning build 20240417 through 5.2.3.3006 build 20250108); the QuTS Hero tag suggests that OS may also be in scope, but this is not confirmed by the provided CPE/EUVD data. No user interaction is needed (UI:N) and the attack is network-reachable (AV:N) with low complexity (AC:L), but the administrative-credential prerequisite confines realistic exploitation to insiders or attackers who have already breached the device's admin layer. Impact is limited to denial of service (availability only). |
| Impact | This is a low-to-moderate priority issue that is unlikely to warrant emergency patching. The signals are internally consistent and point toward low real-world risk: the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:H/UI:N) is network-reachable with low complexity, but critically requires PR:H - a fully compromised administrator account - and the only impact is VA:L (limited availability), with no confidentiality or integrity impact. The EPSS score of 0.14% (34th percentile) corroborates low expected exploitation activity. There is no CISA KEV listing and no public exploit identified at time of analysis. The vendor-assigned base score of 5.1 (Medium) aligns with a DoS-only outcome gated behind administrative privileges. The key limiting factor dominates the assessment: an attacker who already holds a QNAP administrator account can typically cause service disruption through far simpler means (e.g., reboot, service shutdown) without needing this specific NULL pointer dereference, which substantially reduces its practical value to an adversary. No conflicting signals were observed between the CVSS vector and the description - both agree that administrative access is a precondition. |
| Exploit ScenarioDerived | An attacker who has already obtained QNAP administrator credentials (via phishing, credential reuse, or a separate prior compromise) sends a crafted request over the network to a vulnerable QTS management interface, triggering a NULL pointer dereference that crashes the affected service or device and causes a denial of service. No public proof-of-concept exploit code has been identified at the time of analysis, and the attack yields only service disruption, not data access or code execution. |
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Alert meAnalysisAIv2 – Oct 18, 2026
NULL pointer dereference in QNAP QTS 5.2.x allows an attacker who already holds a valid administrator account to crash or destabilize the NAS and cause a denial-of-service condition. The flaw is network-reachable and requires no user interaction, but the administrative-credential prerequisite sharply limits exposure to insiders or attackers who have already compromised the admin layer; impact is availability-only. No public exploit code or CISA KEV entry was identified, EPSS is low at 0.14% (34th percentile), and QNAP has released fixed builds starting with QTS 5.2.6.3195 build 20250715; given the admin prerequisite and availability-only impact, this is a low-to-moderate priority item unlikely to warrant emergency patching.
Earlier versions of this analysis (1)
RemediationAI
Upgrade QNAP QTS to 5.2.6.3195 build 20250715 or later, as documented in QNAP security advisory QSA-25-36 (https://www.qnap.com/en/security-advisory/qsa-25-36). Because exploitation requires a valid administrator account, prioritize reducing administrative exposure: restrict the QTS management interface to a trusted management VLAN or VPN rather than exposing it to the internet, enforce multifactor authentication and strong unique administrator credentials, remove or disable unused admin accounts, and monitor for unexpected service crashes or reboots. These controls reduce the likelihood of an attacker obtaining the prerequisite admin access, but they add administrative friction and do not replace patching. Consult QSA-25-36 for any QuTS Hero-specific fixed builds, since the QuTS Hero tag in the intelligence data is not confirmed by the CPE or EUVD entries.
Affected VersionsENISA
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Technical ContextAI · show details
QTS is QNAP's NAS operating system, and the reported defect is a NULL pointer dereference (CWE-476), a memory-safety class in which the software attempts to access or dereference a pointer that is null, typically causing a process or service to terminate. The assessed vector AV:N/AC:L/PR:H/UI:N with availability-only impact indicates the vulnerable path is reachable over the network and requires no user interaction, but is gated behind administrator privileges; successful triggering can therefore produce a denial-of-service condition rather than code execution or data compromise. CPE data enumerates QTS 5.2.0.2737 build 20240417 through 5.2.3.3006 build 20250108, while EUVD describes the affected range as QTS 5.2.x before 5.2.6.3195 build 20250715. The QuTS Hero tag in the intelligence data suggests that OS may also be in scope, but this is not confirmed by the provided CPE or EUVD entries and should be verified against the vendor advisory.
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Requires a pre-existing administrator account so PR:H; network-reachable with no user interaction; NULL pointer dereference yields only partial availability loss (A:L) with no confidentiality or integrity impact.
Primary rating from Vendor (qnapsecurity).
CVSS VectorVendor: qnapsecurity
Lifecycle Timeline
3DescriptionCVE.org
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. If a remote attacker gains an administrator account, they can then exploit the vulnerability to launch a denial-of-service (DoS) attack.
We have already fixed the vulnerability in the following versions: QTS 5.2.6.3195 build 20250715 and later
Executive ViewAI
Organizations using A NULL pointer dereference vulnerability should be aware of moderate risk from CVE-2025-52428, a null pointer dereference vulnerability rated CVSS 4.9. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.
Apply vendor patch. If patching is delayed: enable ASLR/DEP, apply network segmentation.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which
GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed function definitions in the values of
QNAP QTS before 4.2.4 Build 20170313 allows attackers to execute arbitrary commands via unspecified vectors. Rated criti
QNAP QTS before 4.2.4 Build 20170313 allows attackers to gain administrator privileges and obtain sensitive information
QNAP has patched a remote code execution vulnerability affecting the QTS Media Library in all versions prior to QTS 4.2.
QNAP QTS before 4.2.4 Build 20170313 allows attackers to gain administrator privileges and execute arbitrary commands vi
QNAP QTS before 4.2.4 Build 20170313 allows local users to obtain sensitive Domain Administrator password information by
This command injection vulnerability in QTS allows attackers to run arbitrary commands in the compromised application. R
This improper input validation vulnerability allows remote attackers to inject arbitrary code to the system. Rated criti
A prototype pollution vulnerability has been reported to affect several QNAP operating system versions. Rated high sever
A buffer overflow vulnerability in external device function in QNAP QTS version 4.2.6 build 20171026, 4.3.3.0378 build 2
A buffer overflow vulnerability in password function in QNAP QTS version 4.2.6 build 20171026, 4.3.3.0378 build 20171117
EUVD-2025-32438
NVD
CVE.org
EPSS
GitHub PoC
Exploit-DB