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Qsync Central EUVDEUVD-2025-32087

| CVE-2025-33034 MEDIUM
Path Traversal (CWE-22)
2025-10-03 security@qnapsecurity.com.tw
5.3
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 valid Qsync Central user account
  2. Exploit
    Send request with path traversal sequences
  3. Execution
    Service resolves path outside intended directory
  4. Impact
    Read unexpected files or system data

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V5 - File Handling Path canonicalization, traversal prevention
MITRE ATT&CK

2 techniques across 2 tactics: Discovery, Collection

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 first obtain a valid Qsync Central user account (PR:L) on the targeted QNAP device - this authentication requirement, stated explicitly in the description ('if a remote attacker gains a user account'), is the principal limiting factor. No user interaction is needed (UI:N) and the attack is network-reachable with low complexity (AV:N/AC:L), but impact is confined to reading files or system data outside the intended directory (confidentiality only; no write or service disruption). Realistic risk is therefore gated by credential acquisition and limited to information disclosure on devices running Qsync Central versions 4.x below 5.0.0.1.

Impact

This is a medium-severity information-disclosure flaw that signals modest real-world risk rather than an urgent priority. The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N) describes a network-reachable, low-complexity path traversal that nonetheless REQUIRES authentication (PR:L - the description's 'if a remote attacker gains a user account' corroborates this) and yields only limited confidentiality impact (VC:L) with no integrity or availability effect. These signals are internally consistent: the vector and the prose agree on authenticated access and read-only impact. Exploitation-likelihood signals are weak and aligned: EPSS is 0.06% (19th percentile), there is no CISA KEV listing, and no public exploit code was identified in the provided data - so there is no public exploit identified at time of analysis. The one genuine prerequisite - a valid user account - is the main gating factor; combined with low EPSS and no known exploitation, this is a routine-patch item, not an emergency. No major data conflicts exist; the only caveat is that 'unexpected files or system data' is vague about exactly what is exposed.

Exploit ScenarioDerived

An attacker who already holds valid (possibly low-privilege) credentials on a QNAP device running Qsync Central sends a crafted request containing directory-traversal sequences to a file-handling endpoint, causing the service to return files outside the intended directory such as configuration or system data. No public proof-of-concept was identified, and the low complexity (AC:L) means a working request would be straightforward once an account is obtained.

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

Authenticated path traversal in QNAP Qsync Central 4.x before 5.0.0.1 permits a remote attacker who first obtains a valid user account to read files or system data outside the intended directory. The flaw is network-reachable with low complexity but limited to low confidentiality impact, and no public exploit has been identified at time of analysis. QNAP has released Qsync Central 5.0.0.1 (2025/07/09) to fix the issue; EPSS is low at 0.06% (19th percentile).

Earlier versions of this analysis (1)
v1 Mar 13, 2026 - 19:29 CVSS 6.5

RemediationAI

Vendor-released patch: Qsync Central 5.0.0.1 (2025/07/09) and later, available per the QNAP advisory QSA-25-34 at https://www.qnap.com/en/security-advisory/qsa-25-34. Until upgrading, restrict network access to Qsync Central to trusted networks or a VPN, enforce strong authentication and MFA for all Qsync accounts, and review accounts for least privilege; these measures reduce exposure but do not eliminate the traversal flaw and may limit legitimate remote sync functionality. Monitor file-access logs for anomalous reads outside expected sync directories.

Affected VersionsENISA

Qsync Central 4.x <5.0.0.1 ( 2025/07/09 )

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

Qsync Central is QNAP's file synchronization and sharing service for NAS devices. The vulnerability is a CWE-22 path traversal: the application does not adequately canonicalize or restrict user-supplied file paths, allowing directory traversal sequences to escape the intended sync directory. The assessed CVSS:3.1 vector AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N shows that an attacker with a low-privileged account can remotely read limited files without user interaction, while integrity and availability impacts are absent. The CPE cpe:2.3:a:qnap:qsync_central:*:*:*:*:*:*:*:* covers affected 4.x builds prior to 5.0.0.1; the vendor's own CVSS 4.0 score of 5.3 is consistent with the limited information-disclosure impact.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (qnapsecurity) PRIMARY 5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 4.3 MEDIUM

Network-reachable path traversal needing a valid account gives AV:N/AC:L/PR:L/UI:N; read-only file disclosure yields C:L with I:N/A:N and no scope change.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/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
Low
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

3
CVSS changed
Oct 18, 2026 - 21:38 NVD
6.5 (MEDIUM) 5.3 (MEDIUM)
Patch available
Apr 16, 2026 - 05:29 EUVD
5.0.0.1
CVE Published
Oct 03, 2025 - 18:15 nvd
MEDIUM 6.5

DescriptionCVE.org

A path traversal vulnerability has been reported to affect Qsync Central. If a remote attacker gains a user account, they can then exploit the vulnerability to read the contents of unexpected files or system data.

We have already fixed the vulnerability in the following version: Qsync Central 5.0.0.1 ( 2025/07/09 ) and later

Executive ViewAI

Why It Matters

Organizations using A path traversal vulnerability should be aware of notable risk from CVE-2025-33034, a path traversal vulnerability rated CVSS 6.5. This could allow unauthorized file access. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Moderate
Compensating Controls

Apply vendor patch. If patching is delayed: restrict file access via WAF, implement allowlists.

Threat Intelligence Overview

EPSS Score
0.1%
Top 81% exploitable
Prevalence
Medium
QNAP NAS add-on application; common SMB vendor appliance, not universal
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

Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No

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

Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.

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