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QNAP QTS EUVDEUVD-2025-32450

| CVE-2025-52853 MEDIUM
NULL Pointer Dereference (CWE-476)
2025-10-03 security@qnapsecurity.com.tw
5.1
CVSS 4.0 · Vendor: qnapsecurity
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain admin credentials to QNAP device
  2. Exploit
    Send crafted request to management service
  3. Execution
    Trigger NULL pointer dereference
  4. Impact
    Crash 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 valid QNAP administrator account on the target device (CVSS PR:H) - it is a post-authentication NULL pointer dereference reachable over the network against the device management plane. The hard limiting factor is this administrative privilege prerequisite: without admin credentials the flaw cannot be reached, which sharply narrows realistic exploitation to attackers who have already compromised or been granted admin access. Affected products are QTS 5.2.x before 5.2.6.3195 build 20250715 and QuTS hero h5.2.x before h5.2.6.3195 build 20250715; patched builds remove the condition. Impact is limited to availability (a DoS crash) with no data exposure or modification.

Impact

This is a medium-severity, low-priority issue in practice. The CVSS 4.0 base score of 5.1 is driven entirely by a limited availability impact (VA:L) with no confidentiality or integrity impact (VC:N/VI:N), and the vector requires high privileges (PR:H) - the description explicitly states the attacker must already have gained an administrator account. EPSS reinforces low real-world risk at 0.14% (34th percentile), and there is no CISA KEV listing and no public exploit identified, so there is no evidence of active exploitation. The signals are consistent rather than conflicting: a high-privilege, availability-only DoS with low exploitation probability. The practical risk reduces to post-authentication self-inflicted or lateral denial of service - an attacker who holds QNAP admin credentials already has far greater capabilities (full device control) than crashing a service, which makes this flaw of marginal standalone value. No SSVC decision data was provided in the input, so automatable/technical-impact framing cannot be assessed directly, but the required admin privilege strongly argues against automatable widespread exploitation.

Exploit ScenarioDerived

An attacker who has already obtained QNAP administrator credentials (via phishing, credential reuse, or a separate privilege-granting flaw) sends a crafted request over the network to the management interface, triggering a NULL pointer dereference that crashes the affected service and causes a denial of service on the NAS. No public exploit code has been identified, and exploitation is gated by prior administrative access, so this is not a drive-by scenario.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv2 – Oct 18, 2026

A post-authentication NULL pointer dereference in QNAP QTS and QuTS hero 5.2.x lets a remote attacker who already holds a valid administrator account crash the device management plane, causing a denial-of-service condition with no confidentiality or integrity impact. The administrative privilege prerequisite (CVSS PR:H) is the hard limiting factor: without admin credentials the flaw cannot be reached, so realistic exploitation is confined to attackers who have already compromised or been granted admin access. No public exploit code and no CISA KEV listing were identified at time of analysis, and EPSS is low at 0.14% (34th percentile); this is a medium-severity, low-priority issue in practice, and vendor fixes are already available.

Earlier versions of this analysis (1)
v1 Mar 13, 2026 - 19:29 CVSS 4.9

RemediationAI

Vendor-released patch: QTS 5.2.6.3195 build 20250715 and QuTS hero h5.2.6.3195 build 20250715 (and later) resolve the NULL pointer dereference; upgrade via the QNAP firmware update interface or Qfinder Pro, following QSA-25-36 (https://www.qnap.com/en/security-advisory/qsa-25-36). Because exploitation requires an existing administrator account, prioritize credential hygiene alongside patching: rotate admin passwords, remove unused or default accounts, enforce MFA where supported, and eliminate shared admin logins. Reduce exposure by removing the QTS/QuTS hero management interface from direct internet access and restricting it to a VPN or an allow-listed management network, with the trade-off that remote administration then requires VPN connectivity. Disable or restrict services that expose the web admin UI (for example, disable plain HTTP admin access and limit the system management port to trusted subnets), accepting that legitimate remote administrative workflows will need reconfiguration. Monitor NAS logs and system event notifications for unexpected service crashes or restarts of management daemons, which may indicate attempted triggering, and treat any unexplained admin login activity as a precursor requiring immediate investigation.

Affected VersionsENISA

QTS 5.2.x <5.2.6.3195 build 20250715
QuTS hero h5.2.x <h5.2.6.3195 build 20250715

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The root cause is CWE-476, a NULL pointer dereference, in the QNAP QTS/QuTS hero operating system management plane. CPE data enumerates affected QTS builds from 5.2.0.2737 (build 20240417) through 5.2.3.3006 (build 20250108), and EUVD extends the affected range to all QTS 5.2.x before 5.2.6.3195 build 20250715 and QuTS hero h5.2.x before h5.2.6.3195 build 20250715. The flaw is reachable over the network (CVSS:4.0 AV:N / assessed CVSS:3.1 AV:N) but requires high privileges (PR:H), meaning the attacker must already be authenticated as a QNAP administrator; it is therefore a post-authentication crash rather than a pre-auth attack surface. Successful triggering dereferences an invalid pointer in a NAS service, terminating the process and degrading availability only (assessed CVSS:3.1 A:L with C:N/I:N). There is no memory corruption path described that would permit code execution, data disclosure, or configuration tampering, which keeps the practical severity modest despite the network vector.

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Severity by source

Vendor (qnapsecurity) PRIMARY 5.1 MEDIUM
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
vuln.today AI 2.7 LOW

Network-reachable management service (AV:N) but requires an existing administrator account (PR:H), no user interaction, and impact is a limited DoS only, so C:N/I:N/A:L.

3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (qnapsecurity).

CVSS VectorVendor: qnapsecurity

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
High
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

3
CVSS changed
Oct 18, 2026 - 21:38 NVD
4.9 (MEDIUM) 5.1 (MEDIUM)
Patch available
Apr 16, 2026 - 05:29 EUVD
5.2.6.3195
CVE Published
Oct 03, 2025 - 19:15 nvd
MEDIUM 4.9

DescriptionCVE.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

Why It Matters

Organizations using A NULL pointer dereference vulnerability should be aware of moderate risk from CVE-2025-52853, 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.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: enable ASLR/DEP, apply network segmentation.

Threat Intelligence Overview

EPSS Score
0.1%
Top 66% exploitable
Prevalence
Medium
QNAP QTS/QuTS hero NAS appliances common in SMB/prosumer, not ubiquitous enterprise
Data Quality
4 sources
Confidence: Medium

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.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Low

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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.

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