# CVE-2026-26239 — QNAP Systems Inc. File Station 5

> As of 2026-06-17, CVE-2026-26239 is a HIGH-severity vulnerability in QNAP Systems Inc. File Station 5, CVSS v3.1 8.1, EPSS 0.2% (20.6th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-26239, most recently “QNAP QSA-26-10: Multiple Injection and Memory-Safety Vulnerabilities in QTS, QuTS hero, QuTS cloud, QVP, and File Station (CVE-2025-66273, CVE-2026-26240, and 12 others)”.

**Last updated:** 2026-06-17

## What is CVE-2026-26239?

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

The record classifies CVE-2026-26239 under weakness class [CWE-121](https://cwe.mitre.org/data/definitions/121.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 94 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.1 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **CVSS v4.0 base score:** 6.3 (`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:U`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 20.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-06-10, last modified 2026-06-17

## Is CVE-2026-26239 being exploited?

No public exploitation evidence for CVE-2026-26239 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-06-17. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- **QNAP Systems Inc.**: File Station 5

## How to fix CVE-2026-26239

No vendor patch reference has been recorded for CVE-2026-26239 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-26239

1 tracked threat in the Threadlinqs corpus references CVE-2026-26239, either in the campaign’s CVE list or as an indicator on the campaign record.

- [QNAP QSA-26-10: Multiple Injection and Memory-Safety Vulnerabilities in QTS, QuTS hero, QuTS cloud, QVP, and File Station (CVE-2025-66273, CVE-2026-26240, and 12 others)](https://intel.threadlinqs.com/threat/TL-2026-0901) — HIGH · 2026-06-22

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-06-22. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [qnap.com](https://www.qnap.com/en/security-advisory/qsa-26-10)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-26239
Full detection coverage and IOCs for threats exploiting CVE-2026-26239 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp