Cyber Resilience

CVE-2026-26239

MediumUpdated

Published: 10 June 2026

Published
10 June 2026
Modified
17 June 2026
KEV Added
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Patch
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CVSS Score v4 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0029 21.0th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-26239 is a medium-severity Stack-based Buffer Overflow (CWE-121) vulnerability in Qnap File Station. Its CVSS base score is 6.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 21.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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…

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following version: File Station 5 5.5.6.5208 and later

CWE(s)
CWE-121

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Why these techniques?

Buffer overflow with authenticated access enables memory modification for potential privilege escalation or process crashes for DoS via exploitation.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

Affected Assets

qnap
file station
5.5.6.4691 — 5.5.6.5208

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References