High · 8.8 CVE-2026-31432 EUVD-2026-24640GHSA-f75p-6q8j-p2f2

ksmbd: fix OOB write in QUERY_INFO for compound requests

Published Apr 22, 2026 · Updated Oct 30, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.15 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.8 Package: linux-aws-6.14 Package: linux-aws-6.17 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.14 Package: linux-azure-6.17 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.15 Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.14 Package: linux-gcp-6.17 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.17 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-6.8 Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.14 Package: linux-oem-6.17 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.15 Package: linux-oracle-5.3 Package: linux-oracle-5.8 Package: linux-oracle-6.14 Package: linux-oracle-6.17 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.17 Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.14 Package: linux-riscv-6.17 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix OOB write in QUERY_INFO for compound requests

When a compound request such as READ + QUERY_INFO(Security) is received,
and the first command (READ) consumes most of the response buffer,
ksmbd could write beyond the allocated buffer while building a security
descriptor.

The root cause was that smb2_get_info_sec() checked buffer space using
ppntsd_size from xattr, while build_sec_desc() often synthesized a
significantly larger descriptor from POSIX ACLs.

This patch introduces smb_acl_sec_desc_scratch_len() to accurately
compute the final descriptor size beforehand, performs proper buffer
checking with smb2_calc_max_out_buf_len(), and uses exact-sized
allocation + iov pinning.

Affected products

Vendor	Product	Affected	Fixed
Linux	Linux	6.1.71 – < 6.1.191, 5.15.145 – < 5.16, 6.6	6.1.191

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	6.19.12-1	—
Debian 13	linux	6.12.85-1	—
Debian 12	linux	No fix yet	—

Ubuntu

Security tracker ↗

Release	Package	Fixed in	Advisory
Ubuntu Nvidia-BlueField 24.04 LTS	linux-bluefield	6.8.0-1028.33	—
Ubuntu Nvidia-BlueField 22.04 LTS	linux-bluefield	No fix yet	—
Ubuntu 26.04 LTS	linux-nvidia	7.0.0-1006.6	—
Ubuntu 25.10	linux +8	No fix yet	—
Ubuntu 24.04 LTS	linux	6.8.0-136.136	USN-8567-1
Ubuntu 24.04 LTS	linux-aws	6.8.0-1061.64	USN-8595-2
Ubuntu 24.04 LTS	linux-azure	6.8.0-1063.71	USN-8606-1
Ubuntu 24.04 LTS	linux-azure-fde	6.8.0-1062.69	USN-8607-1
Ubuntu 24.04 LTS	linux-gcp	6.8.0-1064.72	USN-8567-1
Ubuntu 24.04 LTS	linux-gke	6.8.0-1059.67	USN-8567-1
Ubuntu 24.04 LTS	linux-gkeop	6.8.0-1046.50	USN-8567-1
Ubuntu 24.04 LTS	linux-ibm	6.8.0-1061.62	USN-8574-3
Ubuntu 24.04 LTS	linux-lowlatency	6.8.0-136.136.2	USN-8574-2
Ubuntu 24.04 LTS	linux-nvidia	6.8.0-1059.62	USN-8596-1
Ubuntu 24.04 LTS	linux-nvidia-lowlatency	6.8.0-1059.62.1	USN-8596-1
Ubuntu 24.04 LTS	linux-nvidia-tegra	6.8.0-1030.31	USN-8574-3
Ubuntu 24.04 LTS	linux-oracle	6.8.0-1058.61	USN-8574-2
Ubuntu 24.04 LTS	linux-raspi	6.8.0-1061.65	USN-8665-1
Ubuntu 24.04 LTS	linux-riscv +27	No fix yet	—
Ubuntu 24.04 LTS	linux-vmware	6.8.0-1008.8	—
Ubuntu 24.04 LTS	linux-xilinx	6.8.0-1033.34	USN-8574-3

Show 9 more (older releases, extended support, other products)

Release	Package	Fixed in	Advisory
Ubuntu 22.04 LTS	linux +49	No fix yet	—
Ubuntu 22.04 LTS	linux-aws-6.8	6.8.0-1061.64~22.04.1	USN-8595-3
Ubuntu 22.04 LTS	linux-azure-6.8	6.8.0-1063.71~22.04.1	USN-8606-1
Ubuntu 22.04 LTS	linux-azure-fde-6.8	6.8.0-1062.69~22.04.1	USN-8609-1
Ubuntu 22.04 LTS	linux-gcp-6.8	6.8.0-1064.72~22.04.1	USN-8567-1
Ubuntu 22.04 LTS	linux-hwe-6.8	6.8.0-136.136~22.04.1	USN-8619-1
Ubuntu 22.04 LTS	linux-ibm-6.8	6.8.0-1061.62~22.04.1	USN-8574-3
Ubuntu 22.04 LTS	linux-lowlatency-hwe-6.8	6.8.0-136.136.2~22.04.1	USN-8574-2
Ubuntu 22.04 LTS	linux-nvidia-6.8	6.8.0-1059.62~22.04.1	USN-8596-1
Ubuntu 22.04 LTS	linux-oracle-6.8	6.8.0-1058.61~22.04.1	USN-8595-1
Ubuntu 22.04 LTS	linux-riscv-6.8	6.8.0-136.136~22.04.3	—
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-raspi-realtime	6.8.0-2050.52	USN-8665-1
Ubuntu Pro Realtime 24.04 LTS	linux-realtime	6.8.1-1056.57	USN-8567-1
Ubuntu Pro Realtime 24.04 LTS	linux-realtime-6.14 +1	No fix yet	—
Ubuntu Pro Realtime 22.04 LTS	linux-realtime +1	No fix yet	—
Ubuntu Pro Realtime 22.04 LTS	linux-realtime-6.8	6.8.1-1056.57~22.04.2	USN-8567-1
Ubuntu Pro FIPS-updates 24.04 LTS	linux-aws-fips	6.8.0-1061.64+fips1	USN-8595-3
Ubuntu Pro FIPS-updates 24.04 LTS	linux-azure-fips	6.8.0-1063.71+fips2	USN-8608-1
Ubuntu Pro FIPS-updates 24.04 LTS	linux-fips	6.8.0-136.136+fips2	USN-8574-2
Ubuntu Pro FIPS-updates 24.04 LTS	linux-gcp-fips	6.8.0-1064.72+fips1	USN-8574-1
Ubuntu Pro FIPS-updates 22.04 LTS	linux-fips +3	No fix yet	—
Ubuntu Pro 20.04 LTS	linux-aws-5.15 +10	No fix yet	—

Advisories 15

USN-8574-3 linux-ibm, linux-ibm-6.8, linux-nvidia-tegra, linux-xilinx vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8595-3 linux-aws-6.8, linux-aws-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8574-2 linux-fips, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8596-1 linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8665-1 linux-raspi, linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8608-1 linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8574-1 linux-gcp-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8595-2 linux-aws vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8595-1 linux-oracle-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
USN-8567-1 linux, linux-gcp, linux-gcp-6.8, linux-gke, linux-gkeop, linux-realtime, linux-realtime-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
USN-8606-1 linux-azure, linux-azure-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
USN-8607-1 linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
USN-8619-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
USN-8609-1 linux-azure-fde-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
WID-SEC-2026-1232 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 25, 2026

References