# CVE-2023-52447: bpf: Defer the free of inner map when necessary

> A use-after-free vulnerability in the Linux kernel BPF subsystem allows attackers to potentially execute arbitrary code or escalate privileges.

- **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:** 22 Feb 2024
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-35453, AZL-35786, BELL-CVE-2023-52447, DEBIAN-CVE-2023-52447, GHSA-wvjr-h8mr-f8gw, UBUNTU-CVE-2023-52447

## What is CVE-2023-52447?

CVE-2023-52447 is a high-severity use after free vulnerability in Linux kernel, published on 22 Feb 2024. 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: Defer the free of inner map when necessary

When updating or deleting an inner map in map array or map htab, the map
may still be accessed by non-sleepable program or sleepable program.
However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map
directly through bpf_map_put(), if the ref-counter is the last one
(which is true for most cases), the inner map will be freed by
ops->map_free() in a kworker. But for now, most .map_free() callbacks
don't use synchronize_rcu() or its variants to wait for the elapse of a
RCU grace period, so after the invocation of ops->map_free completes,
the bpf program which is accessing the inner map may incur
use-after-free problem.

Fix the free of inner map by invoking bpf_map_free_deferred() after both
one RCU grace period and one tasks trace RCU grace period if the inner
map has been removed from the outer map before. The deferment is
accomplished by using call_rcu() or call_rcu_tasks_trace() when
releasing the last ref-counter of bpf map. The newly-added rcu_head
field in bpf_map shares the same storage space with work field to
reduce the size of bpf_map.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-52447?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-52447?

Apply the vendor's patch.

## Is CVE-2023-52447 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-52447 exists.

## 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-2023-52447 and fix it if it is affected.

What it is: CVE-2023-52447 is a high-severity use after free vulnerability in Linux kernel, published on 22 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-52447 exists.

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-2023-52447/ (Markdown: https://insights.sbomify.com/CVE-2023-52447/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52447
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52447
- OSV: https://osv.dev/vulnerability/CVE-2023-52447

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52447/
Summaries are generated and may contain mistakes; the official description above is the record.