SB20260625249 - Use of Uninitialized Variable in Linux kernel net driver

Description

This security bulletin contains information about 1 vulnerability.

1) Use of Uninitialized Variable (CVE-ID: CVE-2026-52940)

CWE-ID: CWE-457 - Use of Uninitialized Variable

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

The vulnerability allows a local user to disclose sensitive information.

The vulnerability exists due to an uninitialized stack memory usage in tun_put_user() when processing reads of non-tunnel packets with a 24-byte vnet header size. A local user can set the vnet header size with TUNSETVNETHDRSZ and read a non-tunnel packet to disclose sensitive information.

Up to 14 bytes of kernel stack memory may be leaked on each read.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/585cb85e9a29185be05f326369573c2663cf4380
• https://git.kernel.org/stable/c/5fd1fa5a4254bfdd70571c77f5e3bcb4e43738d5
• https://git.kernel.org/stable/c/7f2fcff15e99bb852f6967396ed12b38376e2c8d