Buffer overflow in QNAP File Station

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

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (44.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 44.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-26240: held from 0.004 to 0.006.

EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-26240?
CVE-2026-26240 is a critical-severity vulnerability in QNAP File Station, classified under Stack-based Buffer Overflow. CVSS score: 9.1/10. Published 2026-06-10.
How severe is CVE-2026-26240?
Critical severity. CVSS v3 base score is 9.1 out of 10.