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 management 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 hold a QNAP administrator account on the device (CVSS PR:H) - this is the central limiting prerequisite, not a default-reachable condition. Affected deployments are QTS 5.2.x prior to 5.2.6.3195 build 20250715 and QuTS hero h5.2.x prior to h5.2.6.3195 build 20250715. No user interaction is needed (UI:N) and the vector is network-reachable (AV:N), but because administrator privilege is mandatory, unauthenticated or low-privileged remote actors cannot trigger it; the realistic risk is confined to malicious/compromised admins or chaining after a prior account-takeover. Impact is limited to availability (device/service crash); there is no confidentiality or integrity effect. |
| Impact | This is a genuinely low-priority, medium-severity issue rather than an urgent threat. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:H/UI:N) yields a base score of 5.1 (Medium) precisely because it requires PR:H - a pre-existing administrator account - which is the dominant mitigating factor; the only impact is availability (VA:L), with no confidentiality or integrity effect. All signals align and reinforce each other rather than conflict: EPSS is very low (0.14%, 34th percentile), the CVE is NOT in CISA KEV, and no public exploit code is referenced, which is consistent with a flaw that an attacker can only reach after already holding the highest privilege level. No SSVC decision data was supplied. The practical takeaway is that an attacker who already has administrator access can crash the device, but such an attacker generally has far more impactful options already; the real residual risk is primarily post-compromise denial-of-service or an abusive/insider admin. Patch during normal maintenance cycles - this does not warrant emergency response. |
| Exploit ScenarioDerived | An attacker who has already obtained QNAP administrator credentials (for example via phishing, credential reuse, or a separate privilege-escalation flaw) sends a crafted request over the network to the management interface that triggers the NULL pointer dereference, crashing the affected service or the OS and rendering the NAS unavailable. No public proof-of-concept is referenced, and because the attack vector is network-based with low complexity (AV:N/AC:L), exploitation is trivial once admin access is held - but that prerequisite is the real barrier. |
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Alert meAnalysisAIv2 – Oct 18, 2026
Denial of service in QNAP QTS and QuTS hero 5.2.x allows an attacker who already holds a QNAP administrator account to crash the device or service by triggering a NULL pointer dereference. Affected deployments are QTS before 5.2.6.3195 build 20250715 and QuTS hero before h5.2.6.3195 build 20250715; the vector is network-reachable, but PR:H is the central limiting prerequisite. EPSS is 0.14% (34th percentile), no public exploit identified at time of analysis, and QNAP has released fixed builds; overall risk is low-priority and confined to environments where an administrator account is already malicious or compromised.
Earlier versions of this analysis (1)
RemediationAI
QNAP has released vendor patches: upgrade QTS to 5.2.6.3195 build 20250715 or later, and upgrade QuTS hero to h5.2.6.3195 build 20250715 or later, as documented in QSA-25-36 at https://www.qnap.com/en/security-advisory/qsa-25-36. Because exploitation requires an existing administrator account, prioritize reducing administrative exposure: enforce unique strong administrator credentials, remove unnecessary admin accounts, restrict access to the management UI and SSH to trusted networks or VPN, and disable remote administration where it is not required. The trade-off is that restricting the management interface can hinder legitimate remote administration, and disabling remote admin may require on-site or VPN access for maintenance. Monitor for unexpected service or device crashes as a potential indicator, and no vendor workaround beyond upgrading is specified in the available data.
Affected VersionsENISA
Affects your stack
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Technical ContextAI · show details
QNAP QTS and QuTS hero are Linux-based NAS operating system firmware. The issue is CWE-476, a NULL pointer dereference, meaning a code path can dereference a pointer without validating that it is non-NULL, causing the affected service or system process to fault and potentially crash. The assessed CVSS 3.1 vector is AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L, so no user interaction is needed and the attack is network-reachable, but an existing administrator account is mandatory and impact is limited to availability. CPE data enumerates affected QTS builds from 5.2.0.2737 build 20240417 through 5.2.3.3006 build 20250108, while EUVD describes affected ranges as QTS 5.2.x before 5.2.6.3195 build 20250715 and QuTS hero h5.2.x before h5.2.6.3195 build 20250715.
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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 management function (AV:N/AC:L) but requires an administrator account (PR:H); only a crash results, so C:N/I:N and A:L.
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 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-2025-52854, 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-2025-32437
NVD
CVE.org
EPSS
GitHub PoC
Exploit-DB