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 vulnerable 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 on the target device (CVSS PR:H; vendor states 'If a remote attacker gains an administrator account'). This is the dominant limiting factor: without pre-existing administrative access the vulnerability cannot be triggered, so it provides no privilege escalation and only a self-inflicted DoS. No user interaction is required (UI:N) and the vector is network-reachable (AV:N), but the high authentication bar confines realistic exploitation to already-compromised or insider-controlled appliances running affected QTS 5.2.x / QuTS hero h5.2.x builds below 5.2.6.3195 build 20250715. |
| Impact | This is a low-priority vulnerability despite its MEDIUM CVSS base score of 5.1. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L) confirms that exploitation requires HIGH privileges (PR:H) - specifically an administrator account - which the description independently corroborates ('If a remote attacker gains an administrator account'). The only impact is a LOW availability hit (VA:L) from a NULL pointer dereference crash (CWE-476); there is no confidentiality or integrity impact. All exploitation signals point low: EPSS is 0.14% (34th percentile), there is no CISA KEV listing, and no public exploit code has been identified. These signals are mutually consistent - nothing conflicts. The practical significance is that an attacker must already hold full administrative control of the NAS to trigger a self-inflicted denial of service, which offers negligible additional leverage to a threat actor who, by that point, already owns the device. A patch is available from the vendor. No key data is missing or contradictory for this assessment. |
| Exploit ScenarioDerived | An attacker who has already obtained QNAP administrator credentials (e.g., via phishing, credential reuse, or a prior compromise) sends a crafted request over the network that triggers a NULL pointer dereference in the affected QTS/QuTS hero service. The resulting crash causes a denial of service on the NAS appliance. No public exploit code has been identified at time of analysis, and the required admin privilege sharply limits real-world utility. |
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Alert meAnalysisAIv2 – Oct 18, 2026
NULL pointer dereference in QNAP QTS and QuTS hero 5.2.x allows an attacker who already holds a valid administrator account to crash an affected NAS service, producing a denial-of-service condition with low availability impact. The CVSS base score is 5.1, but the high authentication prerequisite sharply limits practical risk; no public exploit code or CISA KEV entry was identified at time of analysis, and EPSS is low at 0.14%. Affected systems are QTS and QuTS hero builds below 5.2.6.3195 build 20250715.
Earlier versions of this analysis (1)
RemediationAI
Upgrade QTS to 5.2.6.3195 build 20250715 or later and QuTS hero to h5.2.6.3195 build 20250715 or later, as documented in QNAP security advisory QSA-25-36 (https://www.qnap.com/en/security-advisory/qsa-25-36). Until patched, restrict administrative access to trusted management networks or VPN, remove or disable unnecessary administrator accounts, and avoid exposing QTS/QuTS hero administrative interfaces directly to the internet; these controls reduce exposure but do not fix the defect and can complicate legitimate remote administration. Because exploitation requires an existing administrator account, credential hygiene and monitoring for anomalous administrator logins are important compensating measures.
Affected VersionsENISA
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Technical ContextAI · show details
QTS and QuTS hero are QNAP's NAS operating systems. The flaw is classified as CWE-476 NULL pointer dereference, meaning a code path fails to validate a pointer before use and dereferences a NULL value, typically causing a process or service crash rather than code execution or data compromise. Public data does not identify the specific affected service, but the vector is network-reachable (AV:N) with high privileges required (PR:H) and no user interaction (UI:N), so the realistic trigger is an administrator intentionally or unintentionally invoking the vulnerable path. CPE strings enumerate QTS 5.2.0.2737 build 20240417 through 5.2.3.3006 build 20250108, while EUVD lists QTS 5.2.x and QuTS hero h5.2.x below the fixed builds.
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- Exploit and PoC references, threat intelligence from 22 sources
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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
Network-reachable (AV:N) and low complexity (AC:L), but requires administrator access so PR:H; only a DoS crash yields A:L with no C/I impact.
Primary rating from Vendor (qnapsecurity).
CVSS VectorVendor: qnapsecurity
Lifecycle Timeline
4DescriptionCVE.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 QuTS hero h5.2.6.3195 build 20250715 and later
Executive ViewAI
Organizations using A NULL pointer dereference vulnerability should be aware of moderate risk from CVE-2025-48727, 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-2025-32461
NVD
CVE.org
EPSS
GitHub PoC
Exploit-DB