CVE-2022-50296 UM: cpuinfo: Fix a warning for CONFIG_CPUMASK_OFFSTACK

Medium 5.5 Published 15 Sep 2025 Updated 11 May 2026

A kernel warning triggered by reading /proc/cpuinfo with specific debug configurations can lead to system instability or denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2022-50296?

CVE-2022-50296 is a medium-severity denial of service vulnerability in Linux kernel, published on 15 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

UM: cpuinfo: Fix a warning for CONFIG_CPUMASK_OFFSTACK

When CONFIG_CPUMASK_OFFSTACK and CONFIG_DEBUG_PER_CPU_MAPS is selected, cpu_max_bits_warn() generates a runtime warning similar as below while we show /proc/cpuinfo. Fix this by using nr_cpu_ids (the runtime limit) instead of NR_CPUS to iterate CPUs.

[ 3.052463] ------------[ cut here ]------------ [ 3.059679] WARNING: CPU: 3 PID: 1 at include/linux/cpumask.h:108 show_cpuinfo+0x5e8/0x5f0 [ 3.070072] Modules linked in: efivarfs autofs4 [ 3.076257] CPU: 0 PID: 1 Comm: systemd Not tainted 5.19-rc5+ #1052 [ 3.099465] Stack : 9000000100157b08 9000000000f18530 9000000000cf846c 9000000100154000 [ 3.109127] 9000000100157a50 0000000000000000 9000000100157a58 9000000000ef7430 [ 3.118774] 90000001001578e8 0000000000000040 0000000000000020 ffffffffffffffff [ 3.128412] 0000000000aaaaaa 1ab25f00eec96a37 900000010021de80 900000000101c890 [ 3.138056] 0000000000000000 0000000000000000 0000000000000000 0000000000aaaaaa [ 3.147711] ffff8000339dc220 0000000000000001 0000000006ab4000 0000000000000000 [ 3.157364] 900000000101c998 0000000000000004 9000000000ef7430 0000000000000000 [ 3.167012] 0000000000000009 000000000000006c 0000000000000000 0000000000000000 [ 3.176641] 9000000000d3de08 9000000001639390 90000000002086d8 00007ffff0080286 [ 3.186260] 00000000000000b0 0000000000000004 0000000000000000 0000000000071c1c [ 3.195868] ... [ 3.199917] Call Trace: [ 3.203941] [<90000000002086d8>] show_stack+0x38/0x14c [ 3.210666] [<9000000000cf846c>] dump_stack_lvl+0x60/0x88 [ 3.217625] [<900000000023d268>] __warn+0xd0/0x100 [ 3.223958] [<9000000000cf3c90>] warn_slowpath_fmt+0x7c/0xcc [ 3.231150] [<9000000000210220>] show_cpuinfo+0x5e8/0x5f0 [ 3.238080] [<90000000004f578c>] seq_read_iter+0x354/0x4b4 [ 3.245098] [<90000000004c2e90>] new_sync_read+0x17c/0x1c4 [ 3.252114] [<90000000004c5174>] vfs_read+0x138/0x1d0 [ 3.258694] [<90000000004c55f8>] ksys_read+0x70/0x100 [ 3.265265] [<9000000000cfde9c>] do_syscall+0x7c/0x94 [ 3.271820] [<9000000000202fe4>] handle_syscall+0xc4/0x160 [ 3.281824] ---[ end trace 8b484262b4b8c24c ]---

Which versions are affected by CVE-2022-50296?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2022-50296?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2022-50296 being exploited?

There is no known exploitation of CVE-2022-50296 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as DEBIAN-CVE-2022-50296, GHSA-f29r-j658-qgfg, UBUNTU-CVE-2022-50296.