SB2026041419 - Improper input validation in Linux kernel bridge

Description

This security bulletin contains information about 1 vulnerability.

1) Improper input validation (CVE-ID: CVE-2026-31420)

CWE-ID: CWE-20 - Improper input validation

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

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper input validation in br_mrp_start_test(), br_mrp_start_in_test(), and br_mrp_start_in_test_parse() when processing user-supplied netlink attributes. A local user can supply a zero interval value to cause a denial of service.

A zero interval causes delayed work to be rescheduled with no delay, creating a tight loop that allocates and transmits MRP test frames until system memory is exhausted and the kernel panics via OOM deadlock.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/c9bc352f716d1bebfe43354bce539ec2d0223b30
• https://git.kernel.org/stable/c/fa6e24963342de4370e3a3c9af41e38277b74cf3