Threat Intelligence / CVE / CVE-2026-26240

CVE-2026-26240 — QNAP Systems Inc. File Station 5

CVSS v3.1 9.1 (CRITICAL) · CVSS v4.0 1.3 · EPSS 0.3% (higher than 23.3% of all scored CVEs) · Priority 5.5/10 · Published 2026-06-10

As of 2026-06-17, CVE-2026-26240 is a CRITICAL-severity vulnerability in QNAP Systems Inc. File Station 5, CVSS v3.1 9.1, EPSS 0.3% (23.3th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-26240, 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-2026-26240?

A buffer overflow vulnerability has been reported to affect File Station 5. The remote attackers can then exploit the vulnerability to modify memory or crash processes. We have already fixed the vulnerability in the following version: File Station 5 5.5.6.5243 and later

The record classifies CVE-2026-26240 under weakness class CWE-121. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, 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: 9.1 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
CVSS v4.0 base score: 1.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:U
EPSS (FIRST): 0.3% probability of exploitation in the next 30 days, higher than 23.3% of all scored CVEs
CISA KEV: Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority: 5.5/10 — 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-2026-26240 being exploited?

No public exploitation evidence for CVE-2026-26240 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-2026-26240

No vendor patch reference has been recorded for CVE-2026-26240 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-2026-26240

1 tracked threat in the Threadlinqs corpus references CVE-2026-26240, 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) — 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

Full detection coverage & IOCs for threats exploiting CVE-2026-26240 are available via the Threadlinqs MCP server (Purple tier). View plans →

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