Is CVE-2026-26239 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-26239 being exploited in the wild.

How severe is CVE-2026-26239?

Informational severity, with a CVSS score of 8.7, published 10 June 2026.

Which products and versions are affected?

QNAP Systems, Inc. File Station 5 versions prior to 5.5.6.5208.

Is there a fix for CVE-2026-26239?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-26239 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-26239?

Check whether you run QNAP Systems or Inc. File Station 5 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-26239: QNAP File Station 5 stack-based buffer overflow

CVE-2026-26239 · Severity: info · CVSS 8.7 · Published 2026-06-10

A security vulnerability has been identified in QNAP File Station 5, a web-based tool used for managing files on QNAP storage devices. If an attacker obtains access to a standard user account, they can exploit this flaw to crash system processes or modify sensitive memory. This could lead to a total loss of system availability or unauthorized control over the storage device.

Technologies: QNAP Systems, Inc. File Station 5. Vendors: QNAP Systems, Inc..

Quick answers

Is CVE-2026-26239 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-26239 being exploited in the wild.
How severe is CVE-2026-26239?: Informational severity, with a CVSS score of 8.7, published 10 June 2026.
Which products and versions are affected?: QNAP Systems, Inc. File Station 5 versions prior to 5.5.6.5208.
Is there a fix for CVE-2026-26239?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-26239 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-26239?: Check whether you run QNAP Systems or Inc. File Station 5 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A stack-based buffer overflow (CWE-121) exists in QNAP File Station 5. The vulnerability is reachable over the network and requires the attacker to have authenticated access with a standard user account (PR:L). By sending specially crafted input, an attacker can overflow a buffer on the stack to modify memory or crash processes, potentially leading to arbitrary code execution. The issue is resolved in File Station 5 version 5.5.6.5208 and later.

Affected products

QNAP Systems, Inc. File Station 5 versions prior to 5.5.6.5208

Timeline

2026-06-10: disclosed
2026-06-10: advisory

References

https://www.qnap.com/en/security-advisory/qsa-26-37

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