Description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2
When a valid primary TRANSACT2 response has been received (mid->resp_buf
set, mid->multiRsp true) and a subsequent secondary response causes
cifs_check_trans2() to return false -- either because the SMB header is
invalid (malformed != 0) or because check2ndT2() rejects the PDU --
handle_mid() overwrites mid->resp_buf with the new buffer (leaking the
primary buffer) and, because mid->multiRsp is set, skips the
server->smallbuf/bigbuf NULL-out. When the user thread frees
mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the
demux thread reuses it for the next packet, resulting in a use-after-free.
Combine both early-exit conditions and, when mid->multiRsp is already
set, abort the pending transaction inline: set multiEnd, call
dequeue_mid() with malformed=true, and return true so handle_mid() exits
without touching mid->resp_buf or the server buffer pointers.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 3.6 | 6.18.51 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 7.2.6-1 | — |
| Debian 13 | linux | No fix yet | — |
| Debian 12 | linux | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | No fix yet | — |
| Ubuntu Nvidia-BlueField 22.04 LTS | linux-bluefield | No fix yet | — |
| Ubuntu 26.04 LTS | linux | 7.0.0-42.42 | USN-8959-1 |
| Ubuntu 26.04 LTS | linux-aws | 7.0.0-1016.17 | USN-8959-1 |
| Ubuntu 26.04 LTS | linux-azure | 7.0.0-1020.21 | USN-9019-1 |
| Ubuntu 26.04 LTS | linux-azure-fde | 7.0.0-1019.19 | USN-9020-1 |
| Ubuntu 26.04 LTS | linux-gcp | 7.0.0-1016.18 | USN-8959-1 |
| Ubuntu 26.04 LTS | linux-gke | 7.0.0-1010.11 | USN-9020-1 |
| Ubuntu 26.04 LTS | linux-ibm +1 | 7.0.0-1017.17 | USN-8960-1, USN-8959-1 |
| Ubuntu 26.04 LTS | linux-nvidia +1 | No fix yet | — |
| Ubuntu 26.04 LTS | linux-oracle | 7.0.0-1015.16 | USN-8959-1 |
| Ubuntu 26.04 LTS | linux-raspi | 7.0.0-1023.23 | USN-9021-1 |
| Ubuntu 26.04 LTS | linux-realtime | 7.0.0-43.43.1 | USN-9020-1 |
| Ubuntu 26.04 LTS | linux-riscv | 7.0.0-42.42.1 | — |
| Ubuntu 24.04 LTS | linux +45 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-aws-7.0 | 7.0.0-1017.18~24.04.1 | USN-9020-1 |
| Ubuntu 24.04 LTS | linux-azure-fde-7.0 | 7.0.0-1019.19~24.04.1 | USN-9020-1 |
| Ubuntu 24.04 LTS | linux-gcp-7.0 | 7.0.0-1017.19~24.04.1 | USN-9020-1 |
| Ubuntu 24.04 LTS | linux-hwe-7.0 | 7.0.0-42.42~24.04.1 | USN-8959-1 |
| Ubuntu 24.04 LTS | linux-nvidia-tegra | 6.8.0-1038.42 | USN-9002-1 |
| Ubuntu 24.04 LTS | linux-oracle-7.0 | 7.0.0-1016.18~24.04.1 | USN-9020-1 |
| Ubuntu 24.04 LTS | linux-riscv-7.0 | 7.0.0-42.42.1~24.04.1 | — |
| Ubuntu 22.04 LTS | linux +59 | No fix yet | — |
Show 18 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime +3 | No fix yet | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime +2 | No fix yet | — |
| Ubuntu Pro FIPS 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux +21 | No fix yet | — |
| Ubuntu Pro 18.04 LTS | linux +12 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | linux +7 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux +3 | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | kernel-64kb +7 | 6.4.0-150700.53.90.1 | SUSE-SU-2026:5091-1 |
| SLES 15 SP7 | kernel-default-base | 6.4.0-150700.53.90.1.150700.17.51.1 | SUSE-SU-2026:5091-1 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | kernel-64kb +8 | 6.12.0-160000.41.1 | SUSE-SU-2026:24662-1 |
| SLES for SAP 16.0 | kernel-default-base | 6.12.0-160000.41.1.160000.2.32 | SUSE-SU-2026:24662-1 |
| SLES 16.0 | kernel-64kb +8 | 6.12.0-160000.41.1 | SUSE-SU-2026:24662-1, SUSE-SU-2026:24651-1 |
| SLES 16.0 | kernel-default-base | 6.12.0-160000.41.1.160000.2.32 | SUSE-SU-2026:24662-1 |
| SLE Micro 6.2 | kernel-default-base | 6.12.0-160000.41.1.160000.2.32 | SUSE-SU-2026:24643-1 |
| SLE Micro 6.2 | kernel-rt +5 | 6.12.0-160000.41.1 | SUSE-SU-2026:24648-1, SUSE-SU-2026:24643-1 |
| SLE Micro 6.1 | kernel-default-base | 6.4.0-159998.55.1.159998.21.41 | SUSE-SU-2026:24619-1 |
| SLE Micro 6.1 | kernel-source +2 | 6.4.0-159998.55.1 | SUSE-SU-2026:24619-1 |
| SLE Micro 6.0 | kernel-default-base | 6.4.0-159998.55.1.159998.21.42 | SUSE-SU-2026:24550-1 |
| SLE Micro 6.0 | kernel-source +2 | 6.4.0-159998.55.1 | SUSE-SU-2026:24550-1 |
| SLE Live Patching 15 SP7 | kernel-default | 6.4.0-150700.53.90.1 | SUSE-SU-2026:5091-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7_Update_24 | 1-150700.15.3.1 | SUSE-SU-2026:5091-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | kernel-source | 7.2.7-1.1 | openSUSE-SU-2026:11880-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | kernel-livepatch-6.1.188-233.393 +2 | 1:1.0-0.amzn2023 | ALAS2023-2026-3193, ALAS2023-2026-3187, ALAS2023-2026-3183 |
| Amazon Linux 2023 | perf +11 | 1:6.1.188-233.393.amzn2023 | ALAS2023-2026-3183 |
| Amazon Linux 2023 | perf6.12 +11 | 1:6.12.111-136.204.amzn2023 | ALAS2023-2026-3193 |
| Amazon Linux 2023 | perf6.18 +12 | 1:6.18.51-120.162.amzn2023 | ALAS2023-2026-3187 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | kernel | No fix yet | — |
Advisories 18
- USN-9021-1 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- WID-SEC-2026-3321 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- USN-9020-1 linux-aws-7.0, linux-azure-fde, linux-azure-fde-7.0, linux-gcp-7.0, linux-gke, linux-oracle-7.0, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8959-1 linux, linux-aws, linux-gcp, linux-hwe-7.0, linux-ibm, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- SUSE-SU-2026:24662-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 12, 2026
- SUSE-SU-2026:24643-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 12, 2026
- SUSE-SU-2026:24648-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 12, 2026
- SUSE-SU-2026:24651-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 12, 2026
- SUSE-SU-2026:24619-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 12, 2026
- USN-9019-1 linux-azure vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8960-1 linux-oem-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-9002-1 linux-nvidia-tegra vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- SUSE-SU-2026:24550-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 6, 2026
- SUSE-SU-2026:5091-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Nov 4, 2026
- ALAS2023-2026-3193 Important: kernel6.12 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- ALAS2023-2026-3183 Important: kernel security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 22, 2026
- ALAS2023-2026-3187 Important: kernel6.18 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- openSUSE-SU-2026:11880-1 kernel-devel-7.2.7-1.1 on GA media SUSE / openSUSE Security Updates · Sep 25, 2026