CVE-2026-43378

CRITICALNVD 9.87.8▼
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-05-08. NVD baseline CVSS 9.8; sources differ by 2.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.8
EG Score
7.8(medium)
EPSS
22.8%
KEV
Not listed

Published

May 8, 2026

Last Modified

May 20, 2026

Advisory Details (6)

Auto-updated Jun 21, 2026
No patch confirmed yet.
generic

smb: server: fix use-after-free in smb2_open() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e1b21e6066615e7d3d3a7aa2677e415e563fd7cc
generic

smb: server: fix use-after-free in smb2_open() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b720c84087cb547f23ce03eab93568c1769e4556
generic

smb: server: fix use-after-free in smb2_open() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8f5b1a7cb009a93c48e9e334a2f59a660f9afc07
generic

smb: server: fix use-after-free in smb2_open() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/54b48ae83de8bb06e65079d96368efe359d4909c
generic

smb: server: fix use-after-free in smb2_open() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1e689a56173827669a35da7cb2a3c78ed5c53680
generic

smb: server: fix use-after-free in smb2_open() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/190e5f808e8058640b408ccfed25440b441a718a

Vendor Advisories for CVE-2026-43378(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-43378?
CVE-2026-43378 is a critical vulnerability published on May 8, 2026. In the Linux kernel, the following vulnerability has been resolved: smb: server: fix use-after-free in smb2_open() The opinfo pointer obtained via rcudereference(fp->fopinfo) is dereferenced after rcureadunlock(), creating a use-after-free window.
When was CVE-2026-43378 disclosed?
CVE-2026-43378 was first published in the National Vulnerability Database on May 8, 2026, with the most recent update on May 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-43378 actively exploited?
CVE-2026-43378 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 22.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-43378?
CVE-2026-43378 has a CVSS v3 base score of 9.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 7.8.
How do I remediate CVE-2026-43378?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-43378, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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