Description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: require 3 sub-authorities before reading sub_auth[2]
parse_dacl() compares each ACE SID against sid_unix_NFS_mode and on
match reads sid.sub_auth[2] as the file mode. If sid_unix_NFS_mode is
the prefix S-1-5-88-3 with num_subauth = 2 then compare_sids() compares
only min(num_subauth, 2) sub-authorities so a client SID with
num_subauth = 2 and sub_auth = {88, 3} will match.
If num_subauth = 2 and the ACE is placed at the very end of the security
descriptor, sub_auth[2] will be 4 bytes past end_of_acl. The
out-of-band bytes will then be masked to the low 9 bits and applied as
the file's POSIX mode, probably not something that is good to have
happen.
Fix this up by forcing the SID to actually carry a third sub-authority
before reading it at all.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 5.15 | 6.1.175 |
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 | 6.19.14-1 | — |
| Debian 13 | linux | 6.12.85-1 | — |
| Debian 12 | linux | 6.1.176-1 | — |
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 | 7.0.0-27.27 | USN-8488-1 |
| Ubuntu 26.04 LTS | linux-aws | 7.0.0-1008.8 | USN-8488-1 |
| Ubuntu 26.04 LTS | linux-azure | 7.0.0-1010.10 | USN-8603-1 |
| Ubuntu 26.04 LTS | linux-gcp +1 | 7.0.0-1007.7 | USN-8488-1 |
| Ubuntu 26.04 LTS | linux-ibm +1 | 7.0.0-1009.9 | USN-8603-1, USN-8488-1 |
| Ubuntu 26.04 LTS | linux-nvidia | 7.0.0-1013.13 | USN-8507-1 |
| Ubuntu 26.04 LTS | linux-raspi | 7.0.0-1014.14 | USN-8488-2 |
| Ubuntu 26.04 LTS | linux-riscv +1 | 7.0.0-27.27.1 | USN-8488-1 |
| 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-hwe-7.0 | 7.0.0-28.28~24.04.1 | USN-8569-1 |
| 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 10 more (older releases, extended support, other products)Fewer releases
| 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 FIPS-preview 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux-aws-5.15 +10 | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | kernel-source | 7.0.3-1.1 | openSUSE-SU-2026:10703-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | kernel | 6.6.137.1-1 | — |
Advisories 24
- USN-8574-2 linux-fips, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8596-1 linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8607-1 linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8608-1 linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8595-1 linux-oracle-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8595-3 linux-aws-6.8, linux-aws-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8603-1 linux-azure, linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8609-1 linux-azure-fde-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8595-2 linux-aws vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8574-1 linux-gcp-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8574-3 linux-ibm, linux-ibm-6.8, linux-nvidia-tegra, linux-xilinx vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8619-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8665-1 linux-raspi, linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- USN-8606-1 linux-azure, linux-azure-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- WID-SEC-2026-1279 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 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-8488-1 linux, linux-aws, linux-gcp, linux-ibm, linux-oracle, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8569-1 linux-hwe-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8488-2 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8507-1 linux-nvidia vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- ICSA-26-295-16 Siemens SIMATIC S7-1500 TM MFP CISA ICS & IT advisories · Oct 22, 2026
- WID-SEC-2026-3891 Siemens SIMATIC S7: Mehrere Schwachstelle BSI CERT-Bund (WID) · Oct 18, 2026
- SSA-784472 SSA-784472: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1 Siemens ProductCERT · Oct 13, 2026
- openSUSE-SU-2026:10703-1 kernel-devel-7.0.3-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2026
References
- https://git.kernel.org/stable/c/cf2148b880fb7c0fcd727202dbc4fd5d6998b9c2
- https://git.kernel.org/stable/c/b5b5d5936a50497fb151c0b122899a6894721c2b
- https://git.kernel.org/stable/c/08f9e6d899b5c834bbcc239eae1bed58d9b15d2c
- https://git.kernel.org/stable/c/d2454f4a002d08560a60f214f392e6491cf11560
- https://git.kernel.org/stable/c/46bbcd3ebfb3549c8da1838fc4493e79bd3241e7
- https://git.kernel.org/stable/c/9401f86a224f37b50e6a3ccf1d46a70d5ef8af0a
- https://git.kernel.org/stable/c/53370cf9090777774e07fd9a8ebce67c6cc333ab