# CVE-2026-74382: net/sched: cls_bpf: prevent unbounded recursion in offload rollback

> A local attacker with high privileges can cause a kernel stack overflow and system crash by triggering unbounded recursion in the cls_bpf offload rollback mechanism.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74382, DEBIAN-CVE-2026-74382, GHSA-v8p9-m6wc-2cv3, UBUNTU-CVE-2026-74382

## What is CVE-2026-74382?

CVE-2026-74382 is a denial of service vulnerability in Linux, published on 15 Aug 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:

net/sched: cls_bpf: prevent unbounded recursion in offload rollback

Quan Sun reported [1] a stack overflow in cls_bpf_offload_cmd().

Reproducer on netdevsim: add a skip_sw cls_bpf filter, set the
bpf_tc_accept debugfs knob to 0, then `tc filter replace`. The replace
calls tc_setup_cb_replace() which fails. cls_bpf_offload_cmd() then
swaps prog/oldprog and recursively calls itself to roll back. But
bpf_tc_accept=0 makes the rollback fail too, which triggers yet another
rollback frame with the same arguments, and so on until the stack is
exhausted.

bpf_tc_accept is just a convenient knob for the reproducer. Any driver
whose tc_setup_cb_replace() fails twice in a row can hit the same loop,
so this is not a netdevsim-only issue.

Two ways to fix it:

  1) Have the rollback call tc_setup_cb_add() on oldprog instead of
     re-entering cls_bpf_offload_cmd().
  2) Mark the rollback frame with a flag and skip a second-level
     rollback from inside it.

Go with (2). It is the smaller change and keeps the original behaviour:
the rollback still goes through tc_setup_cb_replace(), so the driver
gets one real chance to restore its state. If that attempt also fails,
we just return the original error instead of recursing.

[1]: https://lore.kernel.org/bpf/ce5a6005-3c5e-4696-9e05-eba9461dc860@std.uestc.edu.cn/T/#u

## Which versions are affected by CVE-2026-74382?


## How do I fix CVE-2026-74382?

Apply the vendor's patch.

## Is CVE-2026-74382 being exploited?

There is no known exploitation of CVE-2026-74382 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74382 and fix it if it is affected.

What it is: CVE-2026-74382 is a denial of service vulnerability in Linux, published on 15 Aug 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-2026-74382 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-2026-74382/ (Markdown: https://insights.sbomify.com/CVE-2026-74382/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74382
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74382
- OSV: https://osv.dev/vulnerability/CVE-2026-74382

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74382/
Summaries are generated and may contain mistakes; the official description above is the record.