SB2026110853 - Missing Authorization in Linux kernel net driver

Description

This security bulletin contains information about 1 vulnerability.

1) Missing Authorization (CVE-ID: CVE-2026-99281)

CWE-ID: CWE-862 - Missing Authorization

CVSSv4: 8.5 [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]

The vulnerability allows a local user to gain unauthorized access to TUN/TAP network devices.

The vulnerability exists due to a missing capability check in the Linux kernel TUN/TAP device attachment logic when neither an owner nor a group is assigned to a device. A local user can open an accessible /dev/net/tun device node and attach to an existing ownerless and groupless device without CAP_NET_ADMIN to gain unauthorized access to its packet interface.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/2f92c0286cfd58bff9d6d54c01a771073d5eb775
• https://git.kernel.org/stable/c/e53d1cf05da8ea58a5743b7ce5894fb51b0b9700
• https://git.kernel.org/stable/c/ffdf678dd16610e3f006dac904bd37c09684673c