CVE-2025-21920 : faille élevée linux linux kernel (CVSS 7.1)

Description

In the Linux kernel, the following vulnerability has been resolved: vlan: enforce underlying device type Currently, VLAN devices can be created on top of non-ethernet devices. Besides the fact that it doesn't make much sense, this also causes a bug which leaks the address of a kernel function to usermode. When creating a VLAN device, we initialize GARP (garp_init_applicant) and MRP (mrp_init_applicant) for the underlying device. As part of the initialization process, we add the multicast address of each applicant to the underlying device, by calling dev_mc_add. __dev_mc_add uses dev->addr_len to determine the length of the new multicast address. This causes an out-of-bounds read if dev->addr_len is greater than 6, since the multicast addresses provided by GARP and MRP are only 6 bytes long. This behaviour can be reproduced using the following commands: ip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo ip l set up dev gretest ip link add link gretest name vlantest type vlan id 100 Then, the following command will display the address of garp_pdu_rcv: ip maddr show | grep 01:80:c2:00:00:21 Fix the bug by enforcing the type of the underlying device during VLAN device initialization.

En bref

Sévérité: Élevée (CVSS 7.1)
Vecteur CVSS: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Exploitation active: Non signalée par la CISA
Publication: 1 avr. 2025
Dernière mise à jour: 17 juin 2026

Produits concernés

linux linux kernel

Description

En bref

Produits concernés

Références