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Linux Kernel CIFS Client Memory Leak Fixed
UBUNTU-CVE-2026-23205
Summary
A memory leak has been fixed in the Linux kernel's CIFS client, which could cause a system crash when a CIFS file system is unmounted. This issue was specific to certain file system configurations and was not a security bug. Users running Linux systems with CIFS file systems should update to the latest kernel version to resolve the issue.
What to do
No fix is available yet. Check with your software vendor for updates.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| canonical | linux-hwe-edge | All versions | – |
| canonical | linux-aws-5.0 | All versions | – |
| canonical | linux-aws-5.3 | All versions | – |
| canonical | linux-azure | All versions | – |
| canonical | linux-azure-5.3 | All versions | – |
| canonical | linux-azure-edge | All versions | – |
| canonical | linux-gcp | All versions | – |
| canonical | linux-gcp-5.3 | All versions | – |
| canonical | linux-gke-4.15 | All versions | – |
| canonical | linux-gke-5.4 | All versions | – |
| canonical | linux-gkeop-5.4 | All versions | – |
| canonical | linux-hwe | All versions | – |
| canonical | linux-hwe-edge | All versions | – |
| canonical | linux-oem | All versions | – |
| canonical | linux-oracle-5.0 | All versions | – |
| canonical | linux-oracle-5.3 | All versions | – |
| canonical | linux-aws-5.11 | All versions | – |
| canonical | linux-aws-5.13 | All versions | – |
| canonical | linux-aws-5.8 | All versions | – |
| canonical | linux-azure-5.11 | All versions | – |
| canonical | linux-azure-5.13 | All versions | – |
| canonical | linux-azure-5.8 | All versions | – |
| canonical | linux-azure-fde | All versions | – |
| canonical | linux-gcp-5.11 | All versions | – |
| canonical | linux-gcp-5.13 | All versions | – |
| canonical | linux-gcp-5.8 | All versions | – |
| canonical | linux-gke | All versions | – |
| canonical | linux-gke-5.15 | All versions | – |
| canonical | linux-gkeop | All versions | – |
| canonical | linux-gkeop-5.15 | All versions | – |
| canonical | linux-hwe-5.11 | All versions | – |
| canonical | linux-hwe-5.13 | All versions | – |
| canonical | linux-hwe-5.8 | All versions | – |
| canonical | linux-intel-5.13 | All versions | – |
| canonical | linux-oem-5.10 | All versions | – |
| canonical | linux-oem-5.13 | All versions | – |
| canonical | linux-oem-5.14 | All versions | – |
| canonical | linux-oem-5.6 | All versions | – |
| canonical | linux-oracle-5.11 | All versions | – |
| canonical | linux-oracle-5.13 | All versions | – |
| canonical | linux-oracle-5.8 | All versions | – |
| canonical | linux-raspi2 | All versions | – |
| canonical | linux-riscv | All versions | – |
| canonical | linux-riscv-5.11 | All versions | – |
| canonical | linux-riscv-5.8 | All versions | – |
| canonical | linux-allwinner-5.19 | All versions | – |
| canonical | linux-aws-5.19 | All versions | – |
| canonical | linux-aws-6.2 | All versions | – |
| canonical | linux-aws-6.5 | All versions | – |
| canonical | linux-aws-6.8 | All versions | – |
| canonical | linux-azure-5.19 | All versions | – |
| canonical | linux-azure-6.2 | All versions | – |
| canonical | linux-azure-6.5 | All versions | – |
| canonical | linux-azure-6.8 | All versions | – |
| canonical | linux-azure-fde-5.19 | All versions | – |
| canonical | linux-azure-fde-6.2 | All versions | – |
| canonical | linux-azure-fde-6.8 | All versions | – |
| canonical | linux-gcp-5.19 | All versions | – |
| canonical | linux-gcp-6.2 | All versions | – |
| canonical | linux-gcp-6.5 | All versions | – |
| canonical | linux-gcp-6.8 | All versions | – |
| canonical | linux-hwe-5.19 | All versions | – |
| canonical | linux-hwe-6.2 | All versions | – |
| canonical | linux-hwe-6.5 | All versions | – |
| canonical | linux-hwe-6.8 | All versions | – |
| canonical | linux-ibm-6.8 | All versions | – |
| canonical | linux-intel-iot-realtime | All versions | – |
| canonical | linux-lowlatency-hwe-5.19 | All versions | – |
| canonical | linux-lowlatency-hwe-6.2 | All versions | – |
| canonical | linux-lowlatency-hwe-6.5 | All versions | – |
| canonical | linux-lowlatency-hwe-6.8 | All versions | – |
| canonical | linux-nvidia-6.2 | All versions | – |
| canonical | linux-nvidia-6.5 | All versions | – |
| canonical | linux-nvidia-6.8 | All versions | – |
| canonical | linux-oem-5.17 | All versions | – |
| canonical | linux-oem-6.0 | All versions | – |
| canonical | linux-oem-6.1 | All versions | – |
| canonical | linux-oem-6.5 | All versions | – |
| canonical | linux-oracle-6.5 | All versions | – |
| canonical | linux-oracle-6.8 | All versions | – |
| canonical | linux-realtime | All versions | – |
| canonical | linux-riscv | All versions | – |
| canonical | linux-riscv-5.19 | All versions | – |
| canonical | linux-riscv-6.5 | All versions | – |
| canonical | linux-riscv-6.8 | All versions | – |
| canonical | linux-starfive-5.19 | All versions | – |
| canonical | linux-starfive-6.2 | All versions | – |
| canonical | linux-starfive-6.5 | All versions | – |
| canonical | linux-realtime-6.8 | All versions | – |
| canonical | linux | All versions | – |
| canonical | linux-aws | All versions | – |
| canonical | linux-aws-6.14 | All versions | – |
| canonical | linux-aws-6.17 | All versions | – |
| canonical | linux-azure | All versions | – |
| canonical | linux-azure-6.11 | All versions | – |
| canonical | linux-azure-6.14 | All versions | – |
| canonical | linux-azure-6.17 | All versions | – |
| canonical | linux-azure-fde | All versions | – |
| canonical | linux-azure-fde-6.14 | All versions | – |
| canonical | linux-azure-fde-6.17 | All versions | – |
| canonical | linux-azure-nvidia | All versions | – |
| canonical | linux-azure-nvidia-6.14 | All versions | – |
| canonical | linux-gcp | All versions | – |
| canonical | linux-gcp-6.11 | All versions | – |
| canonical | linux-gcp-6.14 | All versions | – |
| canonical | linux-gcp-6.17 | All versions | – |
| canonical | linux-gke | All versions | – |
| canonical | linux-gkeop | All versions | – |
| canonical | linux-hwe-6.11 | All versions | – |
| canonical | linux-hwe-6.14 | All versions | – |
| canonical | linux-hwe-6.17 | All versions | – |
| canonical | linux-ibm | All versions | – |
| canonical | linux-lowlatency | All versions | – |
| canonical | linux-lowlatency-hwe-6.11 | All versions | – |
| canonical | linux-nvidia | All versions | – |
| canonical | linux-nvidia-6.11 | All versions | – |
| canonical | linux-nvidia-lowlatency | All versions | – |
| canonical | linux-nvidia-tegra | All versions | – |
| canonical | linux-oem-6.11 | All versions | – |
| canonical | linux-oem-6.14 | All versions | – |
| canonical | linux-oem-6.17 | All versions | – |
| canonical | linux-oem-6.8 | All versions | – |
| canonical | linux-oracle | All versions | – |
| canonical | linux-oracle-6.14 | All versions | – |
| canonical | linux-oracle-6.17 | All versions | – |
| canonical | linux-raspi | All versions | – |
| canonical | linux-raspi-realtime | All versions | – |
| canonical | linux-realtime | All versions | – |
| canonical | linux-riscv | All versions | – |
| canonical | linux-riscv-6.14 | All versions | – |
| canonical | linux-riscv-6.17 | All versions | – |
| canonical | linux-xilinx | All versions | – |
| canonical | linux-aws-fips | All versions | – |
| canonical | linux-azure-fips | All versions | – |
| canonical | linux-fips | All versions | – |
| canonical | linux-gcp-fips | All versions | – |
| canonical | linux-raspi-realtime | All versions | – |
| canonical | linux-realtime | All versions | – |
| canonical | linux-realtime-6.14 | All versions | – |
| canonical | linux | All versions | – |
| canonical | linux-aws | All versions | – |
| canonical | linux-azure | All versions | – |
| canonical | linux-azure-fde | All versions | – |
| canonical | linux-gcp | All versions | – |
| canonical | linux-oracle | All versions | – |
| canonical | linux-raspi | All versions | – |
| canonical | linux-realtime | All versions | – |
| canonical | linux-riscv | All versions | – |
Original title
In the Linux kernel, the following vulnerability has been resolved: smb/client: fix memory leak in smb2_open_file() Reproducer: 1. server: directories are exported read-only 2. client: mount -t...
Original description
In the Linux kernel, the following vulnerability has been resolved: smb/client: fix memory leak in smb2_open_file() Reproducer: 1. server: directories are exported read-only 2. client: mount -t cifs //${server_ip}/export /mnt 3. client: dd if=/dev/zero of=/mnt/file bs=512 count=1000 oflag=direct 4. client: umount /mnt 5. client: sleep 1 6. client: modprobe -r cifs The error message is as follows: ============================================================================= BUG cifs_small_rq (Not tainted): Objects remaining on __kmem_cache_shutdown() ----------------------------------------------------------------------------- Object 0x00000000d47521be @offset=14336 ... WARNING: mm/slub.c:1251 at __kmem_cache_shutdown+0x34e/0x440, CPU#0: modprobe/1577 ... Call Trace: <TASK> kmem_cache_destroy+0x94/0x190 cifs_destroy_request_bufs+0x3e/0x50 [cifs] cleanup_module+0x4e/0x540 [cifs] __se_sys_delete_module+0x278/0x400 __x64_sys_delete_module+0x5f/0x70 x64_sys_call+0x2299/0x2ff0 do_syscall_64+0x89/0x350 entry_SYSCALL_64_after_hwframe+0x76/0x7e ... kmem_cache_destroy cifs_small_rq: Slab cache still has objects when called from cifs_destroy_request_bufs+0x3e/0x50 [cifs] WARNING: mm/slab_common.c:532 at kmem_cache_destroy+0x16b/0x190, CPU#0: modprobe/1577
- https://ubuntu.com/security/CVE-2026-23205 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-23205 Third Party Advisory
- https://git.kernel.org/linus/e3a43633023e3cacaca60d4b8972d084a2b06236 Third Party Advisory
- https://git.kernel.org/stable/c/3a6d6b332f92990958602c1e35ce0173e2dd62e9 Third Party Advisory
- https://git.kernel.org/stable/c/743f70406264348c0830f38409eb6c40a42fb2db Third Party Advisory
- https://git.kernel.org/stable/c/9ee608a64e37cea5b4b13e436c559dd0fb2ad1b5 Third Party Advisory
- https://git.kernel.org/stable/c/b64e3b5d8d759dd4333992e4ba4dadf9359952c8 Third Party Advisory
- https://git.kernel.org/stable/c/e3a43633023e3cacaca60d4b8972d084a2b06236 Third Party Advisory
Published: 14 Feb 2026 · Updated: 13 Mar 2026 · First seen: 9 Mar 2026