Which versions of QNAP File Station 5 are affected by EUVD-2026-35979?

QNAP File Station 5 (versions 5.5.0-5.5.6.5208) is vulnerable to a buffer overflow that allows authenticated users to crash processes and corrupt data on NAS systems; no public exploit identified at…. A patch is available.

How to fix or mitigate EUVD-2026-35979?

24 hours: Identify all QNAP File Station 5 deployments and document current software versions. 7 days: Apply vendor-released patch to all systems running versions 5.5.0 through 5.5.6.5208; validate patch in non-production environment before production deployment. 30 days: Complete patching of all affected systems and perform post-patch functionality verification.

QNAP File Station 5 EUVD-2026-35979

Q: What is the CVSS score of EUVD-2026-35979?

EUVD-2026-35979 has a CVSS 4.0 base score of 8.7 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

| CVE-2026-26239 HIGH

Stack-based Buffer Overflow (CWE-121)

2026-06-10 qnap

GHSA-82g9-7jh6-77wg

Stack Overflow Buffer Overflow File Station 5

8.7

CVSS 4.0 · Vendor: qnap

Severity by source

Vendor (qnap) PRIMARY

8.7 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from Vendor (qnap) · only source for this CVE.

CVSS VectorVendor: qnap

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Jun 10, 2026 - 06:20 vuln.today

Patch available

Jun 10, 2026 - 05:01 EUVD

CVSS changed

Jun 10, 2026 - 04:22 NVD

8.7 (HIGH)

CVE Published

Jun 10, 2026 - 03:15 nvd

UNKNOWN (no severity yet)

DescriptionCVE.org

A buffer overflow vulnerability has been reported to affect File Station 5. If a remote attacker gains a user account, they can then exploit the vulnerability to modify memory or crash processes.

We have already fixed the vulnerability in the following version: File Station 5 5.5.6.5208 and later

AnalysisAI

Stack-based buffer overflow in QNAP File Station 5 versions 5.5.0 through 5.5.6.5208 allows authenticated remote attackers to corrupt memory and crash processes on affected NAS deployments. CVSS 4.0 score of 8.7 reflects high impact across confidentiality, integrity, and availability, though exploitation requires valid user credentials (PR:L). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access

Identify internet-exposed QNAP NAS

Delivery

Obtain low-privilege user credentials

Exploit

Authenticate to File Station 5 web UI

Execution

Send crafted oversized request

Persist

Overflow stack buffer in File Station handler

Impact

Corrupt memory and crash process or alter execution

Access

Identify internet-exposed QNAP NAS

Delivery

Obtain low-privilege user credentials

Exploit

Authenticate to File Station 5 web UI

Execution

Send crafted oversized request

Persist

Overflow stack buffer in File Station handler

Impact

Corrupt memory and crash process or alter execution

Vulnerability AssessmentAI

Exploitation	Attacker must possess valid credentials for any user account on the target QNAP NAS (CVSS PR:L), and the File Station 5 app must be installed and reachable on a version between 5.5.0 and 5.5.6.5208 - File Station is bundled by default on QTS/QuTS hero but can be uninstalled. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment	The CVSS 4.0 vector AV:N/AC:L/AT:N/PR:L/UI:N indicates network-reachable, low-complexity exploitation requiring only a low-privilege account and no user interaction, with VC:H/VI:H/VA:H reflecting full compromise of confidentiality, integrity, and availability on the vulnerable subsystem - yielding the 8.7 score. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker phishes, brute-forces, or otherwise obtains credentials for any low-privilege NAS user on an internet-reachable QNAP appliance, logs in to File Station 5 over HTTP(S), and submits a crafted request - likely an oversized filename, path, or parameter - that overflows a stack buffer in the File Station handler. The immediate result is memory corruption causing the File Station process to crash (denial of service); given CWE-121 and the high integrity/confidentiality impact in the CVSS vector, escalation to code execution in the File Station process context is plausible but not confirmed by the vendor description.
Remediation	Vendor-released patch: File Station 5 version 5.5.6.5208 or later - upgrade via the QNAP App Center on each affected NAS, as directed in QSA-26-37 (https://www.qnap.com/en/security-advisory/qsa-26-37). … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

24 hours: Identify all QNAP File Station 5 deployments and document current software versions. …

Threat intelligence, references, and detailed analysis are available after sign-in.

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