CVE-2026-43379 (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is being accessed after rcu_read_unlock() has been called. This creates a race condition where the memory could be freed by a concurrent writer between the unlock and the subsequent pointer dereferences (opinfo->is_lease, etc.), leading to a use-after-free.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0006

Probability of exploitation

0.19%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/960699317d39f46611f4ebeb69edc567c1f4e6b6 https://git.kernel.org/stable/c/b3568347c51c46e2cabc356bc34676df98296619 https://git.kernel.org/stable/c/bf4d66d72e4a9e268c1012c331ce9eaedb5e2086 https://git.kernel.org/stable/c/dbbd328cf58261ca239756fe1c0d10c9518d3399 https://git.kernel.org/stable/c/eac3361e3d5dd8067b3258c69615888eb45e9f25

Frequently Asked Questions

What is CVE-2026-43379? +

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is being accessed after rcu_read_unlock() has been called. This creates a race condition where the memory could be freed by a concurrent writer between the unlock and the subsequent pointer dereferences (opinfo->is_lease, etc.), leading to a use-after-free. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-43379? +

CVE-2026-43379 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0006, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-43379? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-43379