# CVE-2026-93182: sched/fair: Fix overflow in update_tg_cfs_runnable()

> An integer overflow in the Linux kernel scheduler can lead to a divide-by-zero crash, causing a local denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102744, BELL-CVE-2026-93182, DEBIAN-CVE-2026-93182, GHSA-8vpp-69hw-pqmm, UBUNTU-CVE-2026-93182

## What is CVE-2026-93182?

CVE-2026-93182 is a vulnerability in Linux, published on 17 Sep 2026. 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: Fix overflow in update_tg_cfs_runnable()

A divide-by-zero crash is observed when running hackbench:

   [14697.488452] CPU: 112 UID: 0 PID: 124791 Comm: hackbench Not tainted 7.1.0-rc2+
   [14697.492627] RIP: 0010:propagate_entity_load_avg+0x35f/0x3e0
   [14697.506799]  <TASK>
   [14697.507411]  __dequeue_task+0x2b4/0xc70
   [14697.508677]  dequeue_task_fair+0x36/0x370
   [14697.509047]  dequeue_task+0x101/0x2f0
   [14697.509426]  __schedule+0x1b1/0x1a00
   [14697.510868]  anon_pipe_read+0x3da/0x450
   [14697.511400]  vfs_read+0x361/0x390
   [14697.512053]  __x64_sys_read+0x19/0x30

The divide-by-zero happens here:

  if (scale_load_down(gcfs_rq->load.weight)) {
           load_sum = div_u64(gcfs_rq->avg.load_sum,
                              scale_load_down(gcfs_rq->load.weight));
  }

gcfs_rq->load.weight is an insane large value and is truncated
to the lower 32 bits by div_u64, which happen to be 0.

Using AI for investigation, the cause is a u32 overflow in
update_tg_cfs_runnable(), and flat pickup became a victim when using
tg_tasks():

   u32 new_sum, divider;
   ...
   new_sum = se->avg.runnable_avg * divider; <-- boom

The following sequence shows how this triggers the crash:

   propagate_entity_load_avg()
     update_tg_cfs_runnable()     # u32 overflow corrupts runnable_sum

   __update_load_avg_cfs_rq()
     ___update_load_avg()         # computes insane runnable_avg
   update_tg_load_avg()           # propagates to tg->runnable_avg

   update_cfs_group()
     calc_concur_shares()
       tg_tasks()                 # long-to-int truncation, negative nr
     reweight_entity()            # corrupted se->load.weight
       update_load_add()          # corrupted cfs_rq->load.weight

   propagate_entity_load_avg()
     update_tg_cfs_load()
       div_u64()                  # divide-by-zero

Fix by widening new_sum from u32 to u64 (no need to force tg_tasks()
to return unsigned long after this fix)

## Which versions are affected by CVE-2026-93182?


## How do I fix CVE-2026-93182?

Apply the vendor's patch.

## Is CVE-2026-93182 being exploited?

There is no known exploitation of CVE-2026-93182 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93182 and fix it if it is affected.

What it is: CVE-2026-93182 is a vulnerability in Linux, published on 17 Sep 2026. 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-2026-93182 in the wild and no public exploit code.

Affected product: Linux. 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-2026-93182/ (Markdown: https://insights.sbomify.com/CVE-2026-93182/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93182
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93182
- OSV: https://osv.dev/vulnerability/CVE-2026-93182

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93182/
Summaries are generated and may contain mistakes; the official description above is the record.