SB20260912223 - Use-after-free in Linux kernel mpls

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-89555)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 0 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to trigger a use-after-free.

The vulnerability exists due to use-after-free in mpls_multipath_hash when processing MPLS packets with inner IP headers in non-linear data and insufficient tailroom in the linear head. A remote attacker can send a legal Geneve packet through a bareudp/MPLS multipath setup to trigger a use-after-free.

The IPv6 processing path can perform a second pull for the larger header.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650
• https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81
• https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d
• https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad