SB20260325132 - Out-of-bounds read in Linux kernel cxl core driver

Description

This security bulletin contains information about 1 vulnerability.

1) Out-of-bounds read (CVE-ID: CVE-2026-23327)

CWE-ID: CWE-125 - Out-of-bounds read

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to cause a denial of service, disclose sensitive information, and potentially execute arbitrary code.

The vulnerability exists due to improper input validation in the CXL mailbox command handler when processing user-supplied payloads. A local user can send a specially crafted raw mailbox command with an undersized payload to trigger an out-of-bounds read in the kernel, leading to memory disclosure, system crash, or potential code execution.

The issue specifically occurs in the cxl_payload_from_user_allowed() function, where the payload size is not validated before accessing its contents, resulting in a slab-out-of-bounds read during UUID comparison.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/60b5d1f68338aff2c5af0113f04aefa7169c50c2
• https://git.kernel.org/stable/c/7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1