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Vulnerability · Published May 8, 2026 · Assigned by Linux

CVE-2026-43376ksmbd: fix use-after-free by using call_rcu() for oplock_info

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 by using call_rcu() for oplock_info ksmbd currently frees oplock_info immediately using kfree(), even though it is accessed under RCU read-side critical sections in places like opinfo_get() and proc_show_files(). Since there is no RCU grace period delay between nullifying the pointer and freeing the memory, a reader can still access oplock_info structure after it has been freed. This can leads to a use-after-free especially in opinfo_get() where atomic_inc_not_zero() is called on already freed memory. Fix this by switching to deferred freeing using call_rcu().

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13linux6.12.85-1DEBIAN-CVE-2026-43376
Debian:14linux6.19.10-1DEBIAN-CVE-2026-43376
Ubuntu:25.10linux6.17.0-40.40USN-8490-1
Ubuntu:25.10linux6.17.0-40.40UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-aws6.17.0-1019.19USN-8490-1
Ubuntu:25.10linux-aws6.17.0-1019.19UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1019.19~24.04.1UBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1019.19~24.04.1USN-8490-1
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-azureno fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-azure-6.176.17.0-1021.21~24.04.1UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-gcp6.17.0-1020.22UBUNTU-CVE-2026-43376
Ubuntu:25.10linux-gcp6.17.0-1020.22USN-8490-1
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1020.22~24.04.1USN-8490-1
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1020.22~24.04.1UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-40.40~24.04.1USN-8545-1
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-40.40~24.04.1UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1026.26UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1028.28USN-8491-1
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1028.28UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-oracle6.17.0-1018.18USN-8490-1
Ubuntu:25.10linux-oracle6.17.0-1018.18UBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1018.18~24.04.1UBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1018.18~24.04.1USN-8490-1
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-raspi6.17.0-1021.21USN-8546-1
Ubuntu:25.10linux-raspi6.17.0-1021.21UBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-realtime6.17.0-1017.19UBUNTU-CVE-2026-43376
Ubuntu:25.10linux-realtime6.17.0-1017.19USN-8490-2
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-43376
Ubuntu:25.10linux-riscv6.17.0-40.40.1UBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-43376
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-43376
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-43376

Affected products (as reported)

VendorProductVersions
Linux Linux 296cb5457cc6f4a754c4ae29855f8a253d52bcc6 – before 302fef75512b2c8329a3f5efab1ae7ba2562387ad54ab1520d43e95f9b2e22d7a05fc9614192e5a5 – before 08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c18b4fac5ef17f77fed9417d22210ceafd6525fc7 – before 1d6abf145615dbfe267ce3b0a271f95e3780e18e18b4fac5ef17f77fed9417d22210ceafd6525fc7 – before ce8507ee82c888126d8e7565e27c016308d24cde18b4fac5ef17f77fed9417d22210ceafd6525fc7 – before 1dfd062caa165ec9d7ee0823087930f3ab8a6294d73686367ad68534257cd88a36ca3c52cb8b81d86.6.88 – before 6.6.1306.12.25 – before 6.12.78
Linux Linux 6.15

References