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Vulnerability · Published May 8, 2026 · Assigned by Linux

CVE-2026-43379ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()

Critical 9.8

In plain English

A critical-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.4%top 61.2% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13linux6.12.85-1DEBIAN-CVE-2026-43379
Debian:14linux6.19.10-1DEBIAN-CVE-2026-43379
Ubuntu:22.04:LTSlinuxno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinuxno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linuxno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-awsno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-aws-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-azureno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-6.176.17.0-1022.22USN-8636-1
Ubuntu:24.04:LTSlinux-azure-6.176.17.0-1022.22UBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-azure-fde-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-gcpno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1022.25UBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1022.25USN-8636-1
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-gcp-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-42.42USN-8636-1
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-42.42UBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-ibm-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-intel-iotgno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-kvmno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1031.31UBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-nvidia-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-nvidia-lowlatencyno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-nvidia-tegra-igxno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1032.32USN-8636-1
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1032.32UBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-oracleno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1020.20USN-8636-2
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1020.20UBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-raspino fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-realtimeno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-43379
Ubuntu:25.10linux-riscvno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-riscv-6.8no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-vmwareno fix listedUBUNTU-CVE-2026-43379
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-43379
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2026-43379

Affected products (as reported)

VendorProductVersions
Linux Linux 27b40b7bfcd121fe13a150ffe11957630cf49246 – before bf4d66d72e4a9e268c1012c331ce9eaedb5e20865fb282ba4fef8985a5acf2b32681f2ec07732561 – before 960699317d39f46611f4ebeb69edc567c1f4e6b65fb282ba4fef8985a5acf2b32681f2ec07732561 – before dbbd328cf58261ca239756fe1c0d10c9518d33995fb282ba4fef8985a5acf2b32681f2ec07732561 – before b3568347c51c46e2cabc356bc34676df982966195fb282ba4fef8985a5acf2b32681f2ec07732561 – before eac3361e3d5dd8067b3258c69615888eb45e9f256.6.32 – before 6.6.130
Linux Linux 6.9

References