CVE-2026-43490
published 2026-05-15CVE-2026-43490: In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate inherited ACE SID length smb_inherit_dacl() walks the parent directory DACL…
PriorityP352high8.8CVSS 3.1
AVNACLPRLUINSUCHIHAH
EPSS
0.41%
33.4th percentile
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: validate inherited ACE SID length
smb_inherit_dacl() walks the parent directory DACL loaded from the
security descriptor xattr. It verifies that each ACE contains the fixed
SID header before using it, but does not verify that the variable-length
SID described by sid.num_subauth is fully contained in the ACE.
A malformed inheritable ACE can advertise more subauthorities than are
present in the ACE. compare_sids() may then read past the ACE.
smb_set_ace() also clamps the copied destination SID, but used the
unchecked source SID count to compute the inherited ACE size. That could
advance the temporary inherited ACE buffer pointer and nt_size accounting
past the allocated buffer.
Fix this by validating the parent ACE SID count and SID length before
using the SID during inheritance. Compute the inherited ACE size from the
copied SID so the size matches the bounded destination SID. Reject the
inherited DACL if size accumulation would overflow smb_acl.size or the
security descriptor allocation size.
Affected
31 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < a7fb771314fb3a265d30f8ac245869a367ab065c | a7fb771314fb3a265d30f8ac245869a367ab065c |
| linux | linux | >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 47c6e37a77b10e74f70d845ba4ea5d3cafa00336 | 47c6e37a77b10e74f70d845ba4ea5d3cafa00336 |
| linux | linux | >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 1aa60fea7f637c071f529ad6784aecca2f2f0c5f | 1aa60fea7f637c071f529ad6784aecca2f2f0c5f |
| linux | linux | >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < c1d95c995d5bcb24b639200a899eda59cb1e6d64 | c1d95c995d5bcb24b639200a899eda59cb1e6d64 |
| linux | linux | >= e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 < 996454bc0da84d5a1dedb1a7861823087e01a7ae | 996454bc0da84d5a1dedb1a7861823087e01a7ae |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 5.15 < 6.6.141 | 6.6.141 |
| linux | linux_kernel | >= 6.13 < 6.18.30 | 6.18.30 |
| linux | linux_kernel | >= 6.19 < 7.0.7 | 7.0.7 |
| linux | linux_kernel | >= 6.7 < 6.12.88 | 6.12.88 |
| ubuntu | linux | — | — |
| ubuntu | linux-fips | — | — |
| ubuntu | linux-gcp | — | — |
| ubuntu | linux-gcp-6.8 | — | — |
| ubuntu | linux-gcp-fips | — | — |
| ubuntu | linux-gke | — | — |
| ubuntu | linux-gkeop | — | — |
| ubuntu | linux-hwe-7.0 | — | — |
| ubuntu | linux-ibm | — | — |
| ubuntu | linux-lowlatency | — | — |
| ubuntu | linux-lowlatency-hwe-6.8 | — | — |
| ubuntu | linux-nvidia | — | — |
| ubuntu | linux-nvidia-6.8 | — | — |
CVSS provenance
nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_ubuntu7.0HIGH
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It was discovered that some AMD Zen 2 processors did not properly isolate
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the floating point divider unit during speculative execution. A local
attacker could use this to expose sensitive information. (CVE-2025-54505)
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
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It was discovered that some AMD processors did not properly clear data in
the floating point divider unit during speculative execution. A local
attacker could use this to expose sensitive information. (CVE-2025-54505)
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
It was discovered that some AMD Zen 5 processors supporting RDSEED
instruction did not properly handle entropy, potentially resulting in the
consumption of insufficiently random values. A local attacke
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shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- PSP security protocol;
- ARM64 architecture;
- PowerPC architecture;
- RISC-V architecture;
- S390 architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
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Red Hat
kernel: ksmbd: validate inherited ACE SID length
vendor_redhat·2026-05-15
CVE-2026-43490 CWE-805 kernel: ksmbd: validate inherited ACE SID length
kernel: ksmbd: validate inherited ACE SID length
A flaw was found in ksmbd, a Linux kernel module that provides an in-kernel Server Message Block (SMB) server. A remote attacker could exploit this vulnerability by providing a malformed inheritable Access Control Entry (ACE) within a security descriptor. This could lead to an out-of-bounds read or write operation, potentially causing a denial of service (DoS) or information disclosure. The flaw occurs because the system does not properly validate the length of the Security Identifier (SID) within the ACE during inheritance.
Package: kernel (Red Hat Enterprise Linux 10) - Not affected
Package: kernel (Red Hat Enterprise Linux 6) - Not affected
Package: kernel (Red Hat Enterprise Linux 7) - Not affected
Package: kernel-rt (Red Hat Enterp
GHSA
GHSA-9hm7-v4rj-6wqj: In the Linux kernel, the following vulnerability has been resolved:
ksmbd: validate inherited ACE SID length
smb_inherit_dacl() walks the parent dir
ghsa_unreviewed·2026-05-15
CVE-2026-43490 GHSA-9hm7-v4rj-6wqj: In the Linux kernel, the following vulnerability has been resolved:
ksmbd: validate inherited ACE SID length
smb_inherit_dacl() walks the parent dir
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: validate inherited ACE SID length
smb_inherit_dacl() walks the parent directory DACL loaded from the
security descriptor xattr. It verifies that each ACE contains the fixed
SID header before using it, but does not verify that the variable-length
SID described by sid.num_subauth is fully contained in the ACE.
A malformed inheritable ACE can advertise more subauthorities than are
present in the ACE. compare_sids() may then read past the ACE.
smb_set_ace() also clamps the copied destination SID, but used the
unchecked source SID count to compute the inherited ACE size. That could
advance the temporary inherited ACE buffer pointer and nt_size accounting
past the allocated buffer.
Fix this by validating the parent AC
VulDB
Linux Kernel up to 6.12.87/6.18.29/7.0.6/7.1-rc2 ksmbd smb_inherit_dacl buffer overflow (Nessus ID 314946 / WID-SEC-2026-1555)
vuldb·2026-05-15
CVE-2026-43490 [CRITICAL] Linux Kernel up to 6.12.87/6.18.29/7.0.6/7.1-rc2 ksmbd smb_inherit_dacl buffer overflow (Nessus ID 314946 / WID-SEC-2026-1555)
A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.12.87/6.18.29/7.0.6/7.1-rc2. This impacts the function smb_inherit_dacl of the component ksmbd. Such manipulation leads to buffer overflow.
This vulnerability is uniquely identified as CVE-2026-43490. The attack can only be initiated within the local network. No exploit exists.
You should upgrade the affected component.
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/1aa60fea7f637c071f529ad6784aecca2f2f0c5fhttps://git.kernel.org/stable/c/47c6e37a77b10e74f70d845ba4ea5d3cafa00336https://git.kernel.org/stable/c/996454bc0da84d5a1dedb1a7861823087e01a7aehttps://git.kernel.org/stable/c/a7fb771314fb3a265d30f8ac245869a367ab065chttps://git.kernel.org/stable/c/c1d95c995d5bcb24b639200a899eda59cb1e6d64
2026-05-15
Published