Cyber Resilience

CVE-2026-43378

Critical

Published: 08 May 2026

Published
08 May 2026
Modified
20 May 2026
KEV Added
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Patch
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CVSS Score v3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0031 22.6th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-43378 is a critical-severity Use After Free (CWE-416) vulnerability in Linux Linux Kernel. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation of Remote Services (T1210); ranked at the 22.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

In the Linux kernel, the following vulnerability has been resolved: smb: server: fix use-after-free in smb2_open() The opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is dereferenced after rcu_read_unlock(), creating a use-after-free window.

CWE(s)
CWE-416

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
Why these techniques?

UAF in Linux kernel SMB server (smb2_open) enables remote exploitation of SMB service for privilege escalation or RCE.

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

Affected Assets

linux
linux kernel
7.0 · 5.15 — 6.1.167 · 6.2 — 6.6.130 · 6.7 — 6.12.78

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

References