# CVE-2026-43115: srcu: Use irq_work to start GP in tiny SRCU

> A use-after-free vulnerability in the Linux kernel's tiny SRCU implementation allows attackers to potentially execute code or cause a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 6 May 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-43115, DEBIAN-CVE-2026-43115, GHSA-vj6f-v49f-r83x, ROOT-OS-DEBIAN-11-CVE-2026-43115, ROOT-OS-DEBIAN-12-CVE-2026-43115, ROOT-OS-DEBIAN-13-CVE-2026-43115, ROOT-OS-UBUNTU-2204-CVE-2026-43115, ROOT-OS-UBUNTU-2404-CVE-2026-43115, UBUNTU-CVE-2026-43115

## What is CVE-2026-43115?

CVE-2026-43115 is a medium-severity use after free vulnerability in Linux kernel, published on 6 May 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:

srcu: Use irq_work to start GP in tiny SRCU

Tiny SRCU's srcu_gp_start_if_needed() directly calls schedule_work(),
which acquires the workqueue pool->lock.

This causes a lockdep splat when call_srcu() is called with a scheduler
lock held, due to:

  call_srcu() [holding pi_lock]
    srcu_gp_start_if_needed()
      schedule_work() -> pool->lock

  workqueue_init() / create_worker() [holding pool->lock]
    wake_up_process() -> try_to_wake_up() -> pi_lock

Also add irq_work_sync() to cleanup_srcu_struct() to prevent a
use-after-free if a queued irq_work fires after cleanup begins.

Tested with rcutorture SRCU-T and no lockdep warnings.

[ Thanks to Boqun for similar fix in patch "rcu: Use an intermediate irq_work
to start process_srcu()" ]

## Which versions are affected by CVE-2026-43115?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43115?

Apply the vendor's patch.

## Is CVE-2026-43115 being exploited?

There is no known exploitation of CVE-2026-43115 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-2026-43115 and fix it if it is affected.

What it is: CVE-2026-43115 is a medium-severity use after free vulnerability in Linux kernel, published on 6 May 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-2026-43115 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-2026-43115/ (Markdown: https://insights.sbomify.com/CVE-2026-43115/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43115
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43115
- OSV: https://osv.dev/vulnerability/CVE-2026-43115

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43115/
Summaries are generated and may contain mistakes; the official description above is the record.