How severe is CVE-2026-26240?

CVE-2026-26240 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2026-26240 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26240?

CVE-2026-26240 affects Qnap File Station. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26240?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-26240 have an EU (EUVD) identifier?

Yes. CVE-2026-26240 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35983.

When was CVE-2026-26240 published?

CVE-2026-26240 was published on 2026-06-10 and last updated on 2026-06-17.

CVE-2026-26240

CVE-2026-26240 is a critical-severity vulnerability in Qnap File Station with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-121.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 1.3
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-35983
Weakness: CWE-121
Affected product: Qnap File Station
Published: 2026-06-10
Last modified: 2026-06-17

Description

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

Frequently asked questions

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
How severe is CVE-2026-26240?: CVE-2026-26240 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2026-26240 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26240?: CVE-2026-26240 affects Qnap File Station. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26240?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-26240 have an EU (EUVD) identifier?: Yes. CVE-2026-26240 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35983.
When was CVE-2026-26240 published?: CVE-2026-26240 was published on 2026-06-10 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-26-10

Affected products (1)

cpe:2.3:a:qnap:file_station:*:*:*:*:*:*:*:*

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