# CVE-2023-52986: bpf, sockmap: Check for any of tcp_bpf_prots when cloning a listener

> A local attacker can cause a kernel infinite recursion and denial of service by cloning a TCP listener socket linked to a sockmap with specific BPF programs attached.

- **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:** 27 Mar 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-52986, DEBIAN-CVE-2023-52986, GHSA-3m27-46p7-w7mh, UBUNTU-CVE-2023-52986

## What is CVE-2023-52986?

CVE-2023-52986 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Mar 2025. 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, sockmap: Check for any of tcp_bpf_prots when cloning a listener

A listening socket linked to a sockmap has its sk_prot overridden. It
points to one of the struct proto variants in tcp_bpf_prots. The variant
depends on the socket's family and which sockmap programs are attached.

A child socket cloned from a TCP listener initially inherits their sk_prot.
But before cloning is finished, we restore the child's proto to the
listener's original non-tcp_bpf_prots one. This happens in
tcp_create_openreq_child -> tcp_bpf_clone.

Today, in tcp_bpf_clone we detect if the child's proto should be restored
by checking only for the TCP_BPF_BASE proto variant. This is not
correct. The sk_prot of listening socket linked to a sockmap can point to
to any variant in tcp_bpf_prots.

If the listeners sk_prot happens to be not the TCP_BPF_BASE variant, then
the child socket unintentionally is left if the inherited sk_prot by
tcp_bpf_clone.

This leads to issues like infinite recursion on close [1], because the
child state is otherwise not set up for use with tcp_bpf_prot operations.

Adjust the check in tcp_bpf_clone to detect all of tcp_bpf_prots variants.

Note that it wouldn't be sufficient to check the socket state when
overriding the sk_prot in tcp_bpf_update_proto in order to always use the
TCP_BPF_BASE variant for listening sockets. Since commit
b8b8315e39ff ("bpf, sockmap: Remove unhash handler for BPF sockmap usage")
it is possible for a socket to transition to TCP_LISTEN state while already
linked to a sockmap, e.g. connect() -> insert into map ->
connect(AF_UNSPEC) -> listen().

[1]: https://lore.kernel.org/all/00000000000073b14905ef2e7401@google.com/

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2023-52986?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-52986?

Apply the vendor's patch.

## Is CVE-2023-52986 being exploited?

There is no known exploitation of CVE-2023-52986 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-2023-52986 and fix it if it is affected.

What it is: CVE-2023-52986 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Mar 2025. 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-2023-52986 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-2023-52986/ (Markdown: https://insights.sbomify.com/CVE-2023-52986/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52986
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52986
- OSV: https://osv.dev/vulnerability/CVE-2023-52986

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52986/
Summaries are generated and may contain mistakes; the official description above is the record.