# CVE-2026-52938: bpf: Fix NULL pointer dereference in bpf_sk_storage_clone and diag paths

> A NULL pointer dereference in the Linux kernel's BPF socket storage allows attackers to cause a system crash via concurrent network operations.

- **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:** 24 Jun 2026
- **Updated:** 27 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-52938, GHSA-vgrc-x22q-wc53, UBUNTU-CVE-2026-52938

## What is CVE-2026-52938?

CVE-2026-52938 is a medium-severity vulnerability in Linux kernel, published on 24 Jun 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: Fix NULL pointer dereference in bpf_sk_storage_clone and diag paths

bpf_selem_unlink_nofail() sets SDATA(selem)->smap to NULL before
removing the selem from the storage hlist. A concurrent RCU reader in
bpf_sk_storage_clone() can observe the selem still on the list with
smap already NULL, causing a NULL pointer dereference.

 general protection fault, probably for non-canonical address 0xdffffc000000000a:
 KASAN: null-ptr-deref in range [0x0000000000000050-0x0000000000000057]
 RIP: 0010:bpf_sk_storage_clone+0x1cd/0xaa0 net/core/bpf_sk_storage.c:174
 Call Trace:
  <IRQ>
  sk_clone+0xfed/0x1980 net/core/sock.c:2591
  inet_csk_clone_lock+0x30/0x760 net/ipv4/inet_connection_sock.c:1222
  tcp_create_openreq_child+0x35/0x2680 net/ipv4/tcp_minisocks.c:571
  tcp_v4_syn_recv_sock+0x123/0xf90 net/ipv4/tcp_ipv4.c:1729
  tcp_check_req+0x8e1/0x2580 include/net/tcp.h:855
  tcp_v4_rcv+0x1845/0x3b80 net/ipv4/tcp_ipv4.c:2347

Add a NULL check for smap in bpf_sk_storage_clone().

bpf_sk_storage_diag_put_all() has the same issue. Add a NULL check
and pass the validated smap directly to diag_get(), which is refactored
to take smap as a parameter instead of reading it internally.

bpf_sk_storage_diag_put() uses diag->maps[i] which is always valid
under its refcount, so diag->maps[i] is passed directly to diag_get().

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-52938?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52938?

Apply the vendor's patch.

## Is CVE-2026-52938 being exploited?

There is no known exploitation of CVE-2026-52938 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-2026-52938 and fix it if it is affected.

What it is: CVE-2026-52938 is a medium-severity vulnerability in Linux kernel, published on 24 Jun 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-2026-52938 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-2026-52938/ (Markdown: https://insights.sbomify.com/CVE-2026-52938/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52938
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52938
- OSV: https://osv.dev/vulnerability/CVE-2026-52938

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52938/
Summaries are generated and may contain mistakes; the official description above is the record.