CVE-2022-49958: In the Linux kernel, the following vulnerability has been resolved: net/sched: fix netdevice reference leaks in attach_default_qdiscs() In attach_de...

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: fix netdevice reference leaks in attach_default_qdiscs() In attach_default_qdiscs(), if a dev has multiple queues and queue 0 fails to attach qdisc because there is no memory in attach_one_default_qdisc(). Then dev->qdisc will be noop_qdisc by default. But the other queues may be able to successfully attach to default qdisc. In this case, the fallback to noqueue process will be triggered. If the original attached qdisc is not released and a new one is directly attached, this will cause netdevice reference leaks. The following is the bug log: veth0: default qdisc (fq_codel) fail, fallback to noqueue unregister_netdevice: waiting for veth0 to become free. Usage count = 32 leaked reference. qdisc_alloc+0x12e/0x210 qdisc_create_dflt+0x62/0x140 attach_one_default_qdisc.constprop.41+0x44/0x70 dev_activate+0x128/0x290 __dev_open+0x12a/0x190 __dev_change_flags+0x1a2/0x1f0 dev_change_flags+0x23/0x60 do_setlink+0x332/0x1150 __rtnl_newlink+0x52f/0x8e0 rtnl_newlink+0x43/0x70 rtnetlink_rcv_msg+0x140/0x3b0 netlink_rcv_skb+0x50/0x100 netlink_unicast+0x1bb/0x290 netlink_sendmsg+0x37c/0x4e0 sock_sendmsg+0x5f/0x70 ____sys_sendmsg+0x208/0x280 Fix this bug by clearing any non-noop qdiscs that may have been assigned before trying to re-attach.

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.21%

10.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 5.8, < 5.10.142	—
Linux	Linux Kernel	>= 5.11, < 5.15.66	—
Linux	Linux Kernel	>= 5.16, < 5.19.8	—
Linux	Linux Kernel	6.0	Rc1

References

Timeline

Published: Jun 18, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2022-49958?

In the Linux kernel, the following vulnerability has been resolved: net/sched: fix netdevice reference leaks in attach_default_qdiscs() In attach_default_qdiscs(), if a dev has multiple queues and queue 0 fails to attach qdisc because there is no memory in attach_one_default_qdisc(). Then dev->qdisc will be noop_qdisc by default. But the other queues may be able to successfully attach to default qdisc. In this case, the fallback to noqueue process will be triggered. If the original attached qdisc is not released and a new one is directly attached, this will cause netdevice reference leaks. The following is the bug log: veth0: default qdisc (fq_codel) fail, fallback to noqueue unregister_netdevice: waiting for veth0 to become free. Usage count = 32 leaked reference. qdisc_alloc+0x12e/0x210 qdisc_create_dflt+0x62/0x140 attach_one_default_qdisc.constprop.41+0x44/0x70 dev_activate+0x128/0x290 __dev_open+0x12a/0x190 __dev_change_flags+0x1a2/0x1f0 dev_change_flags+0x23/0x60 do_setlink+0x332/0x1150 __rtnl_newlink+0x52f/0x8e0 rtnl_newlink+0x43/0x70 rtnetlink_rcv_msg+0x140/0x3b0 netlink_rcv_skb+0x50/0x100 netlink_unicast+0x1bb/0x290 netlink_sendmsg+0x37c/0x4e0 sock_sendmsg+0x5f/0x70 ____sys_sendmsg+0x208/0x280 Fix this bug by clearing any non-noop qdiscs that may have been assigned before trying to re-attach.

How severe is CVE-2022-49958?

CVE-2022-49958 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2022-49958?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.