# CVE-2023-53215: sched/fair: Don't balance task to its current running CPU

> A flaw in the Linux kernel scheduler allows triggering a warning and potential instability when balancing migration-disabled tasks, leading to denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 15 Sep 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53215, DEBIAN-CVE-2023-53215, GHSA-g72f-mhc5-x52v, UBUNTU-CVE-2023-53215

## What is CVE-2023-53215?

CVE-2023-53215 is a high-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:

sched/fair: Don't balance task to its current running CPU

We've run into the case that the balancer tries to balance a migration
disabled task and trigger the warning in set_task_cpu() like below:

 ------------[ cut here ]------------
 WARNING: CPU: 7 PID: 0 at kernel/sched/core.c:3115 set_task_cpu+0x188/0x240
 Modules linked in: hclgevf xt_CHECKSUM ipt_REJECT nf_reject_ipv4 <...snip>
 CPU: 7 PID: 0 Comm: swapper/7 Kdump: loaded Tainted: G           O       6.1.0-rc4+ #1
 Hardware name: Huawei TaiShan 2280 V2/BC82AMDC, BIOS 2280-V2 CS V5.B221.01 12/09/2021
 pstate: 604000c9 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : set_task_cpu+0x188/0x240
 lr : load_balance+0x5d0/0xc60
 sp : ffff80000803bc70
 x29: ffff80000803bc70 x28: ffff004089e190e8 x27: ffff004089e19040
 x26: ffff007effcabc38 x25: 0000000000000000 x24: 0000000000000001
 x23: ffff80000803be84 x22: 000000000000000c x21: ffffb093e79e2a78
 x20: 000000000000000c x19: ffff004089e19040 x18: 0000000000000000
 x17: 0000000000001fad x16: 0000000000000030 x15: 0000000000000000
 x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000000
 x11: 0000000000000001 x10: 0000000000000400 x9 : ffffb093e4cee530
 x8 : 00000000fffffffe x7 : 0000000000ce168a x6 : 000000000000013e
 x5 : 00000000ffffffe1 x4 : 0000000000000001 x3 : 0000000000000b2a
 x2 : 0000000000000b2a x1 : ffffb093e6d6c510 x0 : 0000000000000001
 Call trace:
  set_task_cpu+0x188/0x240
  load_balance+0x5d0/0xc60
  rebalance_domains+0x26c/0x380
  _nohz_idle_balance.isra.0+0x1e0/0x370
  run_rebalance_domains+0x6c/0x80
  __do_softirq+0x128/0x3d8
  ____do_softirq+0x18/0x24
  call_on_irq_stack+0x2c/0x38
  do_softirq_own_stack+0x24/0x3c
  __irq_exit_rcu+0xcc/0xf4
  irq_exit_rcu+0x18/0x24
  el1_interrupt+0x4c/0xe4
  el1h_64_irq_handler+0x18/0x2c
  el1h_64_irq+0x74/0x78
  arch_cpu_idle+0x18/0x4c
  default_idle_call+0x58/0x194
  do_idle+0x244/0x2b0
  cpu_startup_entry+0x30/0x3c
  secondary_start_kernel+0x14c/0x190
  __secondary_switched+0xb0/0xb4
 ---[ end trace 0000000000000000 ]---

Further investigation shows that the warning is superfluous, the migration
disabled task is just going to be migrated to its current running CPU.
This is because that on load balance if the dst_cpu is not allowed by the
task, we'll re-select a new_dst_cpu as a candidate. If no task can be
balanced to dst_cpu we'll try to balance the task to the new_dst_cpu
instead. In this case when the migration disabled task is not on CPU it
only allows to run on its current CPU, load balance will select its
current CPU as new_dst_cpu and later triggers the warning above.

The new_dst_cpu is chosen from the env->dst_grpmask. Currently it
contains CPUs in sched_group_span() and if we have overlapped groups it's
possible to run into this case. This patch makes env->dst_grpmask of
group_balance_mask() which exclude any CPUs from the busiest group and
solve the issue. For balancing in a domain with no overlapped groups
the behaviour keeps same as before.

## Which versions are affected by CVE-2023-53215?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53215?

Apply the vendor's patch.

## Is CVE-2023-53215 being exploited?

There is no known exploitation of CVE-2023-53215 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53215 and fix it if it is affected.

What it is: CVE-2023-53215 is a high-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.
Exploitation: There is no known exploitation of CVE-2023-53215 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-53215/ (Markdown: https://insights.sbomify.com/CVE-2023-53215/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53215
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53215
- OSV: https://osv.dev/vulnerability/CVE-2023-53215

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53215/
Summaries are generated and may contain mistakes; the official description above is the record.