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9.8
CVE-2026-89788: Linux kernel may crash during SMB share disconnection
CVE-2026-89788 · published 25 days ago
Summary
The Linux operating system’s built‑in file‑sharing service (SMB) can mistakenly reuse memory that has already been cleared when a connection is closed, which may cause the server to crash or become unstable. This can affect any system running the Linux kernel that provides SMB file sharing. Install the latest kernel updates from your Linux distribution to fix the problem.
What to do
- Update debian linux to version 7.2.6-1.
- Update linux kernel to version 7.2.6.
- Update linux linux to version 4e30fbd26e84efa2e5cbec4eb11e126ac0c79313 or later.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Debian:12 | debian | linux | All versions |
| Debian:14 | debian | linux |
< 7.2.6-1 Fix: upgrade to 7.2.6-1
|
| – | linux | linux |
< 4e30fbd26e84efa2e5cbec4eb11e126ac0c79313 6.6 |
| Linux | linux | kernel |
>= 6.6.0, < 7.2.6 Fix: upgrade to 7.2.6
|
| Ubuntu:Pro:14.04:LTS | canonical | linux | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | linux-aws | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | linux-azure | All versions |
| Ubuntu:Pro:14.04:LTS | canonical | linux-lts-xenial | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-aws-hwe | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-gcp | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-hwe | All versions |
| Ubuntu:16.04:LTS | canonical | linux-hwe-edge | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-kvm | All versions |
| Ubuntu:Pro:16.04:LTS | canonical | linux-oracle | All versions |
| Ubuntu:Pro:FIPS:16.04:LTS | canonical | linux-fips | All versions |
| Ubuntu:18.04:LTS | canonical | linux-aws-5.0 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-aws-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-aws-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-azure-4.15 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-azure-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-azure-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-azure-edge | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-gcp-4.15 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gcp-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-gcp-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gke-4.15 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gke-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-gkeop-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-hwe-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-ibm-5.4 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-oem | All versions |
| Ubuntu:18.04:LTS | canonical | linux-oracle-5.0 | All versions |
| Ubuntu:18.04:LTS | canonical | linux-oracle-5.3 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-oracle-5.4 | All versions |
| Ubuntu:Pro:18.04:LTS | canonical | linux-raspi-5.4 | All versions |
| Ubuntu:Pro:FIPS-updates:18.04:LTS | canonical | linux-aws-fips | All versions |
| Ubuntu:Pro:FIPS-updates:18.04:LTS | canonical | linux-azure-fips | All versions |
| Ubuntu:Pro:FIPS-updates:18.04:LTS | canonical | linux-gcp-fips | All versions |
| Ubuntu:20.04:LTS | canonical | linux-aws-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-aws-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-aws-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-aws-5.8 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-azure-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-5.8 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-azure-fde | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-azure-fde-5.15 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-bluefield | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gcp-5.11 | All versions |
Showing 50 of 175. Show the rest
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Ubuntu:20.04:LTS | canonical | linux-gcp-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-gcp-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gcp-5.8 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gke | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gke-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gkeop | All versions |
| Ubuntu:20.04:LTS | canonical | linux-gkeop-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-hwe-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-hwe-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-hwe-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-hwe-5.8 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-ibm | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-ibm-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-intel-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-intel-iotg-5.15 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-iot | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-lowlatency-hwe-5.15 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-nvidia-tegra-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.10 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.13 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.14 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oem-5.6 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oracle-5.11 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oracle-5.13 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-oracle-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-oracle-5.8 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-raspi | All versions |
| Ubuntu:20.04:LTS | canonical | linux-raspi2 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-riscv | All versions |
| Ubuntu:20.04:LTS | canonical | linux-riscv-5.11 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-riscv-5.15 | All versions |
| Ubuntu:20.04:LTS | canonical | linux-riscv-5.8 | All versions |
| Ubuntu:Pro:20.04:LTS | canonical | linux-xilinx-zynqmp | All versions |
| Ubuntu:22.04:LTS | canonical | linux-allwinner-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-aws-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-fde-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-fde-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-azure-fde-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-gcp-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-hwe-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-ibm-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-intel-iot-realtime | All versions |
| Ubuntu:22.04:LTS | canonical | linux-intel-iotg | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-lowlatency-hwe-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-tegra | All versions |
| Ubuntu:22.04:LTS | canonical | linux-nvidia-tegra-igx | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-5.17 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-6.0 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-6.1 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oem-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oracle-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-oracle-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-realtime | All versions |
| Ubuntu:22.04:LTS | canonical | linux-riscv-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-riscv-6.5 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-riscv-6.8 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-starfive-5.19 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-starfive-6.2 | All versions |
| Ubuntu:22.04:LTS | canonical | linux-starfive-6.5 | All versions |
| Ubuntu:Pro:Realtime:22.04:LTS | canonical | linux-realtime-6.8 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-aws-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-aws-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-aws-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-fde-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-fde-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-fde-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-nvidia | All versions |
| Ubuntu:24.04:LTS | canonical | linux-azure-nvidia-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-gcp-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-hwe-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-lowlatency-hwe-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-nvidia-lowlatency | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.11 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oem-6.8 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oracle-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oracle-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-oracle-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-raspi-realtime | All versions |
| Ubuntu:24.04:LTS | canonical | linux-riscv-6.14 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-riscv-6.17 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-riscv-7.0 | All versions |
| Ubuntu:24.04:LTS | canonical | linux-xilinx | All versions |
| Ubuntu:Pro:Realtime:24.04:LTS | canonical | linux-realtime-6.14 | All versions |
| Ubuntu:Pro:Realtime:24.04:LTS | canonical | linux-realtime-6.17 | All versions |
| Ubuntu:26.04:LTS | canonical | linux-nvidia-bos | All versions |
| Ubuntu:26.04:LTS | canonical | linux-oem-7.0 | All versions |
| Alpaquita:23 | bellsoft | linux-lts | >= 6.1.182-r0 |
| Alpaquita:25 | bellsoft | linux-lts | >= 6.12.103-r0 |
| Alpaquita:stream | bellsoft | linux-lts | >= 6.18.46-r0 |
Original advisory text
ksmbd: fix tree connection use-after-free in smb2_tree_connect()
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix tree connection use-after-free in smb2_tree_connect()
ksmbd_tree_conn_connect() publishes a new tree connection in
sess->tree_conns with a single reference and returns its pointer to
smb2_tree_connect(). The handler continues to initialize the object and
build the response after publication. A concurrent session logoff can
erase the connection and drop that reference, freeing the object while
the handler still uses it.
BUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90
smb2_tree_connect (fs/smb/server/smb2pdu.c:2872)
handle_ksmbd_work
process_one_work
worker_thread
kthread
After xa_store() succeeds, take a second reference before releasing
tree_conns_lock. The original reference belongs to the xarray entry and
the second belongs to the creating smb2_tree_connect() handler.
Keep the references balanced in every path:
- On normal exit or an error after publication, smb2_tree_connect()
drops its creator reference. Error cleanup also calls
ksmbd_tree_conn_disconnect(), which drops the xarray reference only if
it removes the exact entry.
- SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop
its xarray reference. The request's existing lookup reference remains
owned by the request and is released by the existing cleanup.
- Session LOGOFF removes each entry and drops its xarray reference. If
it wins the race, later cleanup sees that the entry is gone and does
not drop that reference again.
To enforce this ownership, claim the disconnected state and erase the
exact entry atomically under tree_conns_lock. This guarantees one drop
for the xarray reference and one drop by each in-flight user, regardless
of which teardown path wins. If logoff removes the entry before
initialization completes, fail the connect instead of marking the
detached object TREE_CONNECTED.
ksmbd: fix tree connection use-after-free in smb2_tree_connect()
ksmbd_tree_conn_connect() publishes a new tree connection in
sess->tree_conns with a single reference and returns its pointer to
smb2_tree_connect(). The handler continues to initialize the object and
build the response after publication. A concurrent session logoff can
erase the connection and drop that reference, freeing the object while
the handler still uses it.
BUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90
smb2_tree_connect (fs/smb/server/smb2pdu.c:2872)
handle_ksmbd_work
process_one_work
worker_thread
kthread
After xa_store() succeeds, take a second reference before releasing
tree_conns_lock. The original reference belongs to the xarray entry and
the second belongs to the creating smb2_tree_connect() handler.
Keep the references balanced in every path:
- On normal exit or an error after publication, smb2_tree_connect()
drops its creator reference. Error cleanup also calls
ksmbd_tree_conn_disconnect(), which drops the xarray reference only if
it removes the exact entry.
- SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop
its xarray reference. The request's existing lookup reference remains
owned by the request and is released by the existing cleanup.
- Session LOGOFF removes each entry and drops its xarray reference. If
it wins the race, later cleanup sees that the entry is gone and does
not drop that reference again.
To enforce this ownership, claim the disconnected state and erase the
exact entry atomically under tree_conns_lock. This guarantees one drop
for the xarray reference and one drop by each in-flight user, regardless
of which teardown path wins. If logoff removes the entry before
initialization completes, fail the connect instead of marking the
detached object TREE_CONNECTED.
References
- https://git.kernel.org/stable/c/b5ec6c462aab1062cf5d1e667ba7c6442f737055
- https://git.kernel.org/stable/c/4e30fbd26e84efa2e5cbec4eb11e126ac0c79313
- https://security-tracker.debian.org/tracker/CVE-2026-89788 Vendor Advisory
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git Product
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89788... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-89788 Vendor Advisory
- https://ubuntu.com/security/CVE-2026-89788 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-89788 Third Party Advisory
- https://git.kernel.org/linus/b5ec6c462aab1062cf5d1e667ba7c6442f737055 Third Party Advisory
- https://docs.bell-sw.com/security/cves/CVE-2026-89788 Vendor Advisory
Severity
9.8
Critical
Timeline
Published16 Sep 2026
Updated11 Oct 2026
First seen16 Sep 2026
Sources
CVE-2026-89788 · NVD
CVE-2026-89788 · MITRE
DEBIAN-CVE-2026-89788 · OSV
CVE-2026-89788 · OSV
UBUNTU-CVE-2026-89788 · OSV
BELL-CVE-2026-89788 · OSV
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