CVE-2025-21920

HIGH EPSS 8.6%

Published Apr 1, 20251y ago · Modified Jun 17, 20261w ago

7.1 CVSS 3.1

High

Published Apr 1, 2025 1y ago

Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score

7.1

Exploitability

1.8

Impact

5.2

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Attack Vector Local

Attack Complexity Low

Privileges Required Low

User Interaction None

Scope Unchanged

Confidentiality High

Integrity None

Availability High

Threat Intelligence

EPSS Exploit Probability

8.6% percentile

Exploit & Patch Status

No Known Exploit

Patch Available

Weaknesses 1

CWE-125 Out-of-bounds Read Memory Safety

Affected Products 12

Vendor	Product	Version	Range
linux	linux_kernel	*	≥2.6.35 – <5.4.291
linux	linux_kernel	*	≥5.5 – <5.10.235
linux	linux_kernel	*	≥5.11 – <5.15.179
linux	linux_kernel	*	≥5.16 – <6.1.131
linux	linux_kernel	*	≥6.2 – <6.6.83
linux	linux_kernel	*	≥6.7 – <6.12.19
linux	linux_kernel	*	≥6.13 – <6.13.7
linux	linux_kernel	6.14	any
linux	linux_kernel	6.14	any
linux	linux_kernel	6.14	any
linux	linux_kernel	6.14	any
linux	linux_kernel	6.14	any

References 10

git.kernel.org https://git.kernel.org/stable/c/0fb7aa04c19eac4417f360a9f7611a60637bdacc

Patch
git.kernel.org https://git.kernel.org/stable/c/30e8aee77899173a82ae5ed89f536c096f20aaeb

Patch
git.kernel.org https://git.kernel.org/stable/c/3561442599804905c3defca241787cd4546e99a7

Patch
git.kernel.org https://git.kernel.org/stable/c/5a515d13e15536e82c5c7c83eb6cf5bc4827fee5

Patch
git.kernel.org https://git.kernel.org/stable/c/7f1564b2b2072b7aa1ac75350e9560a07c7a44fd

Patch
git.kernel.org https://git.kernel.org/stable/c/b33a534610067ade2bdaf2052900aaad99701353

Patch
git.kernel.org https://git.kernel.org/stable/c/b6c72479748b7ea09f53ed64b223cee6463dc278

Patch
git.kernel.org https://git.kernel.org/stable/c/fa40ebef69234e39ec2d26930d045f2fb9a8cb2b

Patch
lists.debian.org https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
lists.debian.org https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

Remediation

git.kernel.org https://git.kernel.org/stable/c/0fb7aa04c19eac4417f360a9f7611a60637bdacc

Patch
git.kernel.org https://git.kernel.org/stable/c/30e8aee77899173a82ae5ed89f536c096f20aaeb

Patch
git.kernel.org https://git.kernel.org/stable/c/3561442599804905c3defca241787cd4546e99a7

Patch
git.kernel.org https://git.kernel.org/stable/c/5a515d13e15536e82c5c7c83eb6cf5bc4827fee5

Patch
git.kernel.org https://git.kernel.org/stable/c/7f1564b2b2072b7aa1ac75350e9560a07c7a44fd

Patch
git.kernel.org https://git.kernel.org/stable/c/b33a534610067ade2bdaf2052900aaad99701353

Patch
git.kernel.org https://git.kernel.org/stable/c/b6c72479748b7ea09f53ed64b223cee6463dc278

Patch
git.kernel.org https://git.kernel.org/stable/c/fa40ebef69234e39ec2d26930d045f2fb9a8cb2b

Patch