SB20260507156 - Heap-based buffer overflow in Linux kernel smb server

Description

This security bulletin contains information about 1 vulnerability.

1) Heap-based buffer overflow (CVE-ID: CVE-2026-43185)

CWE-ID: CWE-122 - Heap-based Buffer Overflow

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

The vulnerability allows a remote attacker to execute arbitrary code.

The vulnerability exists due to a heap-based buffer overflow in smb_direct_prepare_negotiation() when processing crafted SMB Direct negotiation messages. A remote attacker can send a crafted preferred_send_size value followed by a large second message to execute arbitrary code.

The issue is triggered by a signedness error that causes a malicious preferred_send_size value of 0x80000000 to be treated as smaller than max_recv_size and used to set the allowed receive size for the next message.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/55abc475d096da4a5356b6efb0cfdc6156bc1550
• https://git.kernel.org/stable/c/6b4f875aac344cdd52a1f34cc70ed2f874a65757
• https://git.kernel.org/stable/c/ceae058eb707ddd0d68f0872f9d9f23b7c30c37b