dbcve.org
Linux KernelOperating system · Linux

CVE-2025-21652

HIGH · 7.8 CVSS v3.1 Published 2025-01-19
Fix available
A fix is available. Upgrade to 6.6.72 / 6.12.10 or later.
See remediation →
80/100
Remediation priority · High
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: ipvlan: Fix use-after-free in ipvlan_get_iflink(). syzbot presented an use-after-free report [0] regarding ipvlan and linkwatch. ipvlan does not hold a refcnt of the lower device unlike vlan and macvlan. If the linkwatch work is triggered for the ipvlan dev, the lower dev might have already been freed, resulting in UAF of ipvlan->phy_dev in ipvlan_get_iflink(). We can delay the lower dev unregistration like vlan and macvlan by holding the lower dev's refcnt in dev->netdev_ops->ndo_init() and releasing it in dev->priv_destructor(). Jakub pointed out calling .ndo_XXX after unregister_netdevice() has returned is error prone and suggested [1] addressing this UAF in the core by taking commit 750e51603395 ("net: avoid potential UAF in default_operstate()") further. Let's assume unregistering devices DOWN and use RCU protection in default_operstate() not to race with the device unregistration. [0]: BUG: KASAN: slab-use-after-free in ipvlan_get_iflink+0x84/0x88 drivers/net/ipvlan/ipvlan_main.c:353 Read of size 4 at addr ffff0000d768c0e0 by task kworker/u8:35/6944 CPU: 0 UID: 0 PID: 6944 Comm: kworker/u8:35 Not tainted 6.13.0-rc2-g9bc5c9515b48 #12 4c3cb9e8b4565456f6a355f312ff91f4f29b3c47 Hardware name: linux,dummy-virt (DT) Workqueue: events_unbound linkwatch_event Call trace: show_stack+0x38/0x50 arch/arm64/kernel/stacktrace.c:484 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xbc/0x108 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x16c/0x6f0 mm/kasan/report.c:489 kasan_report+0xc0/0x120 mm/kasan/report.c:602 __asan_report_load4_noabort+0x20/0x30 mm/kasan/report_generic.c:380 ipvlan_get_iflink+0x84/0x88 drivers/net/ipvlan/ipvlan_main.c:353 dev_get_iflink+0x7c/0xd8 net/core/dev.c:674 default_operstate net/core/link_watch.c:45 [inline] rfc2863_policy+0x144/0x360 net/core/link_watch.c:72 linkwatch_do_dev+0x60/0x228 net/core/link_watch.c:175 __linkwatch_run_queue+0x2f4/0x5b8 net/core/link_watch.c:239 linkwatch_event+0x64/0xa8 net/core/link_watch.c:282 process_one_work+0x700/0x1398 kernel/workqueue.c:3229 process_scheduled_works kernel/workqueue.c:3310 [inline] worker_thread+0x8c4/0xe10 kernel/workqueue.c:3391 kthread+0x2b0/0x360 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 Allocated by task 9303: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x30/0x68 mm/kasan/common.c:68 kasan_save_alloc_info+0x44/0x58 mm/kasan/generic.c:568 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x84/0xa0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4283 [inline] __kmalloc_node_noprof+0x2a0/0x560 mm/slub.c:4289 __kvmalloc_node_noprof+0x9c/0x230 mm/util.c:650 alloc_netdev_mqs+0xb4/0x1118 net/core/dev.c:11209 rtnl_create_link+0x2b8/0xb60 net/core/rtnetlink.c:3595 rtnl_newlink_create+0x19c/0x868 net/core/rtnetlink.c:3771 __rtnl_newlink net/core/rtnetlink.c:3896 [inline] rtnl_newlink+0x122c/0x15c0 net/core/rtnetlink.c:4011 rtnetlink_rcv_msg+0x61c/0x918 net/core/rtnetlink.c:6901 netlink_rcv_skb+0x1dc/0x398 net/netlink/af_netlink.c:2542 rtnetlink_rcv+0x34/0x50 net/core/rtnetlink.c:6928 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0x618/0x838 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x5fc/0x8b0 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg net/socket.c:726 [inline] __sys_sendto+0x2ec/0x438 net/socket.c:2197 __do_sys_sendto net/socket.c:2204 [inline] __se_sys_sendto net/socket.c:2200 [inline] __arm64_sys_sendto+0xe4/0x110 net/socket.c:2200 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x90/0x278 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x13c/0x250 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x54/0x70 arch/arm64/kernel/syscall.c:151 el ---truncated---

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-416

Memory is used after it has been freed, so its contents — now potentially attacker-controlled — drive the program's behaviour. With careful heap grooming this becomes code execution. The fix requires disciplined ownership of memory and often a targeted rework of the object lifecycle.

General guidance for the use after free class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.2, < 6.6.72>= 6.7, < 6.12.10= 6.13

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.72 / 6.12.10 or later
Fixed in 6.6.726.12.10
Vendor patch git.kernel.org →
Recommended fix High confidence

6.6.72+ (for 6.2-6.6.x branches), 6.12.10+ (for 6.7-6.12.x branches), or latest stable 6.13.x

  1. 1. Identify the currently running kernel version using `uname -r`
  2. 2. Determine which kernel branch your current version belongs to (6.2-6.6.x, 6.7-6.12.x, or 6.13.x)
  3. 3. For systems running kernel 6.2 to 6.6.x: upgrade to kernel version 6.6.72 or later
  4. 4. For systems running kernel 6.7 to 6.12.x: upgrade to kernel version 6.12.10 or later
  5. 5. For systems running kernel 6.13.x: upgrade to the latest stable kernel version (6.13.2 or later)
  6. 6. Apply the upgrade via standard distribution kernel update mechanism (e.g., `apt update && apt upgrade`, `yum update`, or distribution-specific kernel package manager)
  7. 7. Reboot the system to load the fixed kernel
  8. 8. Verify the fix is applied by checking `ipvlan_get_iflink` symbol is present and running without UAF errors
Caveat Kernel upgrades may require system reboot and could introduce compatibility changes with out-of-tree kernel modules or specific hardware drivers; ensure backup and test in staging if possible

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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Peer-ranked notes from engineers who’ve handled CVE-2025-21652 in production — separate from our analysis above.

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