# CVE-2026-52941: net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint

> Unprivileged users can crash the Linux kernel via SMC-D sockets if the smc_msg_event tracepoint is enabled, causing 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:** 24 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** AZL-90815, BELL-CVE-2026-52941, DEBIAN-CVE-2026-52941, GHSA-x48q-47qq-gv8g, ROOT-OS-UBUNTU-2404-CVE-2026-52941, UBUNTU-CVE-2026-52941

## What is CVE-2026-52941?

CVE-2026-52941 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:

net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint

The smc_msg_event tracepoint class, shared by smc_tx_sendmsg and
smc_rx_recvmsg, unconditionally dereferences smc->conn.lnk:

	__string(name, smc->conn.lnk->ibname)

conn->lnk is only set for SMC-R; for SMC-D it is NULL. Other code on
these paths already handles this (e.g. !conn->lnk in
SMC_STAT_RMB_TX_SIZE_SMALL()). With the tracepoint enabled, the first
sendmsg()/recvmsg() on an SMC-D socket crashes:

  Oops: general protection fault, probably for non-canonical address
  KASAN: null-ptr-deref in range [...]
  RIP: 0010:strlen+0x1e/0xa0
  Call Trace:
   trace_event_raw_event_smc_msg_event (net/smc/smc_tracepoint.h:44)
   smc_rx_recvmsg (net/smc/smc_rx.c:515)
   smc_recvmsg (net/smc/af_smc.c:2859)
   __sys_recvfrom (net/socket.c:2315)
   __x64_sys_recvfrom (net/socket.c:2326)
   do_syscall_64

The faulting address 0x3e0 is offsetof(struct smc_link, ibname),
confirming the NULL ->lnk deref. Enabling the tracepoint requires
root, but the trigger itself is unprivileged: socket(AF_SMC, ...) has
no capability check, and SMC-D negotiation needs no admin step on
s390 or on x86 with the loopback ISM device loaded.

Log an empty device name for SMC-D instead of dereferencing NULL.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-52941?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52941?

Apply the vendor's patch.

## Is CVE-2026-52941 being exploited?

There is no known exploitation of CVE-2026-52941 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-2026-52941 and fix it if it is affected.

What it is: CVE-2026-52941 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-2026-52941 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-2026-52941/ (Markdown: https://insights.sbomify.com/CVE-2026-52941/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52941
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52941
- OSV: https://osv.dev/vulnerability/CVE-2026-52941

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52941/
Summaries are generated and may contain mistakes; the official description above is the record.