CVE-2025-21652: In the Linux kernel, the following vulnerability has been resolved: ipvlan: Fix use-after-free in ipvlan_get

In the Linux kernel, the following vulnerability has been resolved: ipvlan: Fix use-after-free in ipvlan_get_iflink().

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 tai

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.21%, higher than 11% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored November 9, 2026, updated daily.

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Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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