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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未强制VLAN底层设备类型。

AI Predicted 6.5 Difficulty: Moderate EPSS 0.23% · P13

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 22bedad3ce112d5ca1eaf043d4990fa2ed698c87< 7f1564b2b2072b7aa1ac75350e9560a07c7a44fd affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< fa40ebef69234e39ec2d26930d045f2fb9a8cb2b affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< 0fb7aa04c19eac4417f360a9f7611a60637bdacc affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< 5a515d13e15536e82c5c7c83eb6cf5bc4827fee5 affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< 3561442599804905c3defca241787cd4546e99a7 affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< 30e8aee77899173a82ae5ed89f536c096f20aaeb affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< b6c72479748b7ea09f53ed64b223cee6463dc278 affected
22bedad3ce112d5ca1eaf043d4990fa2ed698c87< b33a534610067ade2bdaf2052900aaad99701353 affected
… +10 more rows
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I. Basic Information for CVE-2025-21920

Vulnerability Information
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Vulnerability Title
vlan: enforce underlying device type
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未强制VLAN底层设备类型。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 22bedad3ce112d5ca1eaf043d4990fa2ed698c87 ~ 7f1564b2b2072b7aa1ac75350e9560a07c7a44fd -
Linux Linux 2.6.35 -

II. Public POCs for CVE-2025-21920

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III. Intelligence Information for CVE-2025-21920

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Patches & Fixes for CVE-2025-21920 (2)

Same Patch Batch · Linux · 2025-04-01 · 93 CVEs total

CVE-2025-21927 9.8 CRITICAL nvme-tcp: fix potential memory corruption in nvme_tcp_recv_pdu()
CVE-2025-21954 9.8 CRITICAL netmem: prevent TX of unreadable skbs
CVE-2025-21969 8.8 HIGH Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd
CVE-2025-21955 8.8 HIGH ksmbd: prevent connection release during oplock break notification
CVE-2025-21972 8.8 HIGH net: mctp: unshare packets when reassembling
CVE-2025-21946 8.8 HIGH ksmbd: fix out-of-bounds in parse_sec_desc()
CVE-2025-21945 8.8 HIGH ksmbd: fix use-after-free in smb2_lock
CVE-2025-21967 8.8 HIGH ksmbd: fix use-after-free in ksmbd_free_work_struct
CVE-2025-21947 8.1 HIGH ksmbd: fix type confusion via race condition when using ipc_msg_send_request
CVE-2025-21923 7.8 HIGH HID: hid-steam: Fix use-after-free when detaching device
CVE-2025-21934 7.8 HIGH rapidio: fix an API misues when rio_add_net() fails
CVE-2025-21949 7.8 HIGH LoongArch: Set hugetlb mmap base address aligned with pmd size
CVE-2025-21919 7.8 HIGH sched/fair: Fix potential memory corruption in child_cfs_rq_on_list
CVE-2025-21914 7.8 HIGH slimbus: messaging: Free transaction ID in delayed interrupt scenario
CVE-2025-21924 7.8 HIGH net: hns3: make sure ptp clock is unregister and freed if hclge_ptp_get_cycle returns an e
CVE-2025-21958 7.8 HIGH Revert "openvswitch: switch to per-action label counting in conntrack"
CVE-2025-21965 7.8 HIGH sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()
CVE-2025-21926 7.8 HIGH net: gso: fix ownership in __udp_gso_segment
CVE-2025-21939 7.8 HIGH drm/xe/hmm: Don't dereference struct page pointers without notifier lock
CVE-2025-21985 7.8 HIGH drm/amd/display: Fix out-of-bound accesses

Showing top 20 of 93 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21920

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