# CVE-2026-93173: bpf,lsm: Drop bpf_prog_free from sleepable_lsm_hooks

> A local attacker with high privileges can trigger a kernel bug causing a system crash when freeing BPF programs attached to sleepable LSM hooks.

- **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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-93173, DEBIAN-CVE-2026-93173, GHSA-ggp7-x9rm-wrm3, UBUNTU-CVE-2026-93173

## What is CVE-2026-93173?

CVE-2026-93173 is a denial of service 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:

bpf,lsm: Drop bpf_prog_free from sleepable_lsm_hooks

__bpf_prog_put_rcu() is the call_rcu() callback for non-sleepable programs.
security_bpf_prog_free() called from there fires bpf_prog_free in softirq;
if a sleepable LSM prog is attached to that hook, might_fault() BUGs:

  BUG: sleeping function called from invalid context
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5038
  preempt_count: 101, expected: 0
  Call Trace:
   <IRQ>
   __bpf_prog_enter_sleepable+0x1cd/0x320 kernel/bpf/trampoline.c:1255
   bpf_trampoline_6442549705+0x53/0xd7
   security_bpf_prog_free+0xde/0x130 security/security.c:5465
   __bpf_prog_put_rcu+0xab/0xd0 kernel/bpf/syscall.c:2365
   rcu_do_batch kernel/rcu/tree.c:2617 [inline]
   handle_softirqs+0x236/0x800 kernel/softirq.c:622
   </IRQ>

The call_rcu/call_rcu_tasks_trace split reflects the freed program's
sleepability, not that of any attached observer.

security_bpf_prog_free() also frees prog->aux->security, which has to stay
after the grace period, so drop bpf_prog_free from sleepable_lsm_hooks
rather than move the call. Non-sleepable observers still run there.

## Which versions are affected by CVE-2026-93173?


## How do I fix CVE-2026-93173?

Apply the vendor's patch.

## Is CVE-2026-93173 being exploited?

There is no known exploitation of CVE-2026-93173 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93173 and fix it if it is affected.

What it is: CVE-2026-93173 is a denial of service 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-2026-93173 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-2026-93173/ (Markdown: https://insights.sbomify.com/CVE-2026-93173/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93173
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93173
- OSV: https://osv.dev/vulnerability/CVE-2026-93173

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93173/
Summaries are generated and may contain mistakes; the official description above is the record.