High · 8.8 CVE-2026-72382 EUVD-2026-59281GHSA-xrhm-hwvc-w6q3

ksmbd: reject undersized DACLs before parsing ACEs

Published Aug 15, 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-7.0 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-7.0 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-6.17 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fde-7.0 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-7.0 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-7.0 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-7.0 Package: linux-nvidia-bos 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-oem-7.0 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-oracle-7.0 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-riscv-7.0 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: reject undersized DACLs before parsing ACEs

parse_dacl() limits the attacker-controlled ACE count by comparing it
with the number of minimal ACEs that fit in the DACL size. The DACL size
field is 16 bits, but the expression subtracts sizeof(struct smb_acl).
Because sizeof() is unsigned, a DACL size smaller than the ACL header
underflows to a large size_t.

A malicious client can reach this with:

SMB2_SET_INFO (InfoType=SMB2_O_INFO_SECURITY)
-> smb2_set_info_sec()
-> set_info_sec()
-> parse_sec_desc()
-> parse_dacl()
-> init_acl_state(..., 0xffff)
-> init_acl_state(..., 0xffff)
-> kmalloc_objs(..., 0xffff)

Thus a malformed security descriptor can make num_aces pass the guard
and drive large temporary ACL state and pointer-array allocations.

Reject DACLs smaller than struct smb_acl before doing the subtraction,
so the ACE count check cannot be bypassed by the underflow.

Affected products

Vendor	Product	Affected	Fixed
Linux	Linux	5.15	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	7.1.5-1	—
Debian 13	linux	6.12.100-1	—
Debian 12	linux	No fix yet	—

Ubuntu

Security tracker ↗

Release	Package	Fixed in	Advisory
Ubuntu Nvidia-BlueField 24.04 LTS	linux-bluefield	6.8.0-1033.38	—
Ubuntu Nvidia-BlueField 22.04 LTS	linux-bluefield	No fix yet	—
Ubuntu 26.04 LTS	linux	7.0.0-38.38	USN-8887-1
Ubuntu 26.04 LTS	linux-aws +1	7.0.0-1014.14	USN-8887-1
Ubuntu 26.04 LTS	linux-azure	7.0.0-1017.17	USN-8888-1
Ubuntu 26.04 LTS	linux-azure-fde	7.0.0-1016.16	USN-8888-1
Ubuntu 26.04 LTS	linux-gke	7.0.0-1008.9	USN-8887-1
Ubuntu 26.04 LTS	linux-ibm +1	7.0.0-1015.15	USN-8889-1, USN-8887-1
Ubuntu 26.04 LTS	linux-nvidia	7.0.0-1025.26	USN-9043-1
Ubuntu 26.04 LTS	linux-nvidia-bos	7.0.0-2022.23	USN-9003-1
Ubuntu 26.04 LTS	linux-oracle	7.0.0-1013.13	USN-8887-1
Ubuntu 26.04 LTS	linux-raspi	7.0.0-1023.23	USN-9021-1
Ubuntu 26.04 LTS	linux-riscv +1	7.0.0-38.38.1	USN-8887-1
Ubuntu 24.04 LTS	linux	6.8.0-147.147	USN-8917-1
Ubuntu 24.04 LTS	linux-aws +1	6.8.0-1067.70	USN-9024-1, USN-8917-1
Ubuntu 24.04 LTS	linux-aws-7.0 +1	7.0.0-1014.14~24.04.1	USN-8887-3, USN-8887-2
Ubuntu 24.04 LTS	linux-azure-7.0	7.0.0-1017.17~24.04.1	USN-8888-2
Ubuntu 24.04 LTS	linux-azure-fde	6.8.0-1069.76	USN-8918-1
Ubuntu 24.04 LTS	linux-azure-fde-7.0	7.0.0-1016.16~24.04.1	USN-8888-2
Ubuntu 24.04 LTS	linux-gcp +1	6.8.0-1071.79	USN-8918-1, USN-8917-1
Ubuntu 24.04 LTS	linux-gke	6.8.0-1066.74	USN-8917-1
Ubuntu 24.04 LTS	linux-gkeop	6.8.0-1052.56	USN-8917-1
Ubuntu 24.04 LTS	linux-hwe-7.0	7.0.0-38.38~24.04.4	USN-8887-3
Ubuntu 24.04 LTS	linux-ibm	6.8.0-1067.68	USN-8917-1
Ubuntu 24.04 LTS	linux-lowlatency	6.8.0-147.147.1	USN-8917-1
Ubuntu 24.04 LTS	linux-nvidia-7.0	7.0.0-1024.25~24.04.1	USN-9003-1
Ubuntu 24.04 LTS	linux-nvidia-lowlatency	6.8.0-1067.70.1	USN-9040-1
Ubuntu 24.04 LTS	linux-nvidia-tegra	6.8.0-1036.39	USN-8886-1
Ubuntu 24.04 LTS	linux-oracle	6.8.0-1064.67	USN-8917-1
Ubuntu 24.04 LTS	linux-oracle-7.0	7.0.0-1013.13~24.04.1	USN-8887-3
Ubuntu 24.04 LTS	linux-raspi	6.8.0-1068.72	USN-9025-1
Ubuntu 24.04 LTS	linux-riscv +29	No fix yet	—
Ubuntu 24.04 LTS	linux-riscv-7.0	7.0.0-38.38.1~24.04.1	—
Ubuntu 24.04 LTS	linux-vmware	6.8.0-1008.8	—
Ubuntu 22.04 LTS	linux +50	No fix yet	—
Ubuntu 22.04 LTS	linux-aws-6.8	6.8.0-1069.74~22.04.1	USN-9024-1
Ubuntu 22.04 LTS	linux-azure-6.8	6.8.0-1073.82~22.04.1	USN-9026-1
Ubuntu 22.04 LTS	linux-azure-fde-6.8	6.8.0-1071.78~22.04.1	USN-9026-1
Ubuntu 22.04 LTS	linux-gcp-6.8	6.8.0-1073.81~22.04.1	USN-9024-1
Ubuntu 22.04 LTS	linux-hwe-6.8	6.8.0-149.149~22.04.1	USN-9066-1
Ubuntu 22.04 LTS	linux-ibm-6.8	6.8.0-1069.70~22.04.1	USN-9024-1
Ubuntu 22.04 LTS	linux-lowlatency-hwe-6.8	6.8.0-149.149.1~22.04.1	USN-9024-1
Ubuntu 22.04 LTS	linux-oracle-6.8	6.8.0-1067.71~22.04.1	USN-9025-1

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

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-raspi-realtime	6.8.0-2056.58	USN-9025-1
Ubuntu Pro Realtime 24.04 LTS	linux-realtime	6.8.1-1062.63	USN-8917-1
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	6.8.1-1064.65~22.04.1	USN-9024-1
Ubuntu Pro FIPS-updates 24.04 LTS	linux-aws-fips	6.8.0-1067.70+fips1	USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS	linux-fips	6.8.0-147.147+fips1	USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS	linux-gcp-fips +1	6.8.0-1071.79+fips1	USN-8918-1, USN-8917-1
Ubuntu Pro FIPS-updates 22.04 LTS	linux-fips +3	No fix yet	—
Ubuntu Pro FIPS-preview 22.04 LTS	linux-fips +3	No fix yet	—
Ubuntu Pro 20.04 LTS	linux-aws-5.15 +10	No fix yet	—

Advisories 18

USN-9066-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-9021-1 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-9024-1 linux-aws-6.8, linux-gcp-6.8, linux-ibm-6.8, linux-lowlatency-hwe-6.8, linux-nvidia, linux-realtime-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-9026-1 linux-azure-6.8, linux-azure-fde-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
WID-SEC-2026-2852 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
USN-9040-1 linux-nvidia-lowlatency vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-9043-1 linux-nvidia vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8917-1 linux, linux-aws, linux-aws-fips, linux-fips, linux-gcp, linux-gcp-fips, linux-gke, linux-gkeop, linux-ibm, linux-lowlatency, linux-oracle, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-9025-1 linux-oracle-6.8, linux-raspi, linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8887-1 linux, linux-aws, linux-gcp, linux-gke, linux-ibm, linux-oracle, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-9003-1 linux-nvidia-7.0, linux-nvidia-bos vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8887-3 linux-gcp-7.0, linux-hwe-7.0, linux-oracle-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8888-2 linux-azure-7.0, linux-azure-fde-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8918-1 linux-azure, linux-azure-fde, linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8888-1 linux-azure, linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8887-2 linux-aws-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8889-1 linux-oem-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
USN-8886-1 linux-nvidia-tegra vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026

References