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NVD / CVE Program· CNA Linux

CVE-2025-21920: vlan: enforce underlying device type

HighCVSS 7.1 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 28/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.23% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0fb7aa04c19eac4417f360a9f7611a60637bdacc, 30e8aee77899173a82ae5ed89f536c096f20aaeb, 3561442599804905c3defca241787cd4546e99a7; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.85.1-2; azl3 kernel 6.6.85.1-2 on Azure Linux 3.0 6.6.85.1-2.

Low priority for now. Upgrade to Linux Linux 0fb7aa04c19eac4417f360a9f7611a60637bdacc, 30e8aee77899173a82ae5ed89f536c096f20aaeb, 3561442599804905c3defca241787cd4546e99a7; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.85.1-2; azl3 kernel 6.6.85.1-2 on Azure Linux 3.0 6.6.85.1-2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Apr 1, 2025
Updated
Jun 17, 2026
EPSS
0.2% · 14th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2025-21920

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.35affected
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before 7f1564b2b2072b7aa1ac75350e9560a07c7a44fdaffected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before fa40ebef69234e39ec2d26930d045f2fb9a8cb2baffected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before 0fb7aa04c19eac4417f360a9f7611a60637bdaccaffected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before 5a515d13e15536e82c5c7c83eb6cf5bc4827fee5affected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before 3561442599804905c3defca241787cd4546e99a7affected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before 30e8aee77899173a82ae5ed89f536c096f20aaebaffected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before b6c72479748b7ea09f53ed64b223cee6463dc278affected · git
    • 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 and later · before b33a534610067ade2bdaf2052900aaad99701353affected · git
    • before 2.6.35not affected · semver
Affected versions · NVD (8)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.35 and later · before 5.4.291
  • linux linux kernel5.5 and later · before 5.10.235
  • linux linux kernel5.11 and later · before 5.15.179
  • linux linux kernel5.16 and later · before 6.1.131
  • linux linux kernel6.2 and later · before 6.6.83
  • linux linux kernel6.7 and later · before 6.12.19
  • linux linux kernel6.13 and later · before 6.13.7
  • linux linux kernel6.14

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:9kernelbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64kbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debugbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debug-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debug-develbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debug-devel-matchedbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debug-modulesbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debug-modules-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-debug-modules-extrabefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-develbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-devel-matchedbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-modulesbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-modules-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-64k-modules-extrabefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-abi-stablelistsbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-cross-headersbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-debugbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-debug-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-debug-develbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-debug-devel-matchedbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-debug-modulesbefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6
AlmaLinux:9kernel-debug-modules-corebefore 5.14.0-570.21.1.el9_65.14.0-570.21.1.el9_6

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-21917Apr 1, 2025 · usb: renesas_usbhs: Flush the notify_hotplug_work
    22Monitor
  • ← EarlierCVE-2025-21918Apr 1, 2025 · usb: typec: ucsi: Fix NULL pointer access
    22Monitor
  • Later →CVE-2025-21922Apr 1, 2025 · ppp: Fix KMSAN uninit-value warning with bpf
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0fb7aa04c19eac4417f360a9f7611a60637bdaccVendor (CNA)
Linux Linux30e8aee77899173a82ae5ed89f536c096f20aaebVendor (CNA)
Linux Linux3561442599804905c3defca241787cd4546e99a7Vendor (CNA)
Linux Linux5a515d13e15536e82c5c7c83eb6cf5bc4827fee5Vendor (CNA)
Linux Linux7f1564b2b2072b7aa1ac75350e9560a07c7a44fdVendor (CNA)
Linux Linuxb33a534610067ade2bdaf2052900aaad99701353Vendor (CNA)
Linux Linuxb6c72479748b7ea09f53ed64b223cee6463dc278Vendor (CNA)
Linux Linuxfa40ebef69234e39ec2d26930d045f2fb9a8cb2bVendor (CNA)
azl3 kernel 6.6.82.1-1 on Azure Linux 3.06.6.85.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.85.1-2 on Azure Linux 3.06.6.85.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL-Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.180.1-1 on CBL Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-570.21.1.el9_6 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.133-1 · Debian:12Package registry (OSV)
opensuse:dtb-aarch646.4.0-150600.23.60.3 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-64kb6.4.0-150600.23.60.4 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-azure6.4.0-150600.8.43.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-debug6.4.0-150600.23.60.4 · openSUSE:Leap 15.6Package registry (OSV)

+33

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (9 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records