# CVE-2024-35894: mptcp: prevent BPF accessing lowat from a subflow socket.

> A local attacker can trigger a kernel warning and potential crash by using BPF to access MPTCP lowat from a subflow socket.

- **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:** 19 May 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2024-35894, DEBIAN-CVE-2024-35894, GHSA-pw5g-24rm-mrgw, UBUNTU-CVE-2024-35894

## What is CVE-2024-35894?

CVE-2024-35894 is a high-severity vulnerability in Linux kernel, published on 19 May 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:

mptcp: prevent BPF accessing lowat from a subflow socket.

Alexei reported the following splat:

 WARNING: CPU: 32 PID: 3276 at net/mptcp/subflow.c:1430 subflow_data_ready+0x147/0x1c0
 Modules linked in: dummy bpf_testmod(O) [last unloaded: bpf_test_no_cfi(O)]
 CPU: 32 PID: 3276 Comm: test_progs Tainted: GO       6.8.0-12873-g2c43c33bfd23
 Call Trace:
  <TASK>
  mptcp_set_rcvlowat+0x79/0x1d0
  sk_setsockopt+0x6c0/0x1540
  __bpf_setsockopt+0x6f/0x90
  bpf_sock_ops_setsockopt+0x3c/0x90
  bpf_prog_509ce5db2c7f9981_bpf_test_sockopt_int+0xb4/0x11b
  bpf_prog_dce07e362d941d2b_bpf_test_socket_sockopt+0x12b/0x132
  bpf_prog_348c9b5faaf10092_skops_sockopt+0x954/0xe86
  __cgroup_bpf_run_filter_sock_ops+0xbc/0x250
  tcp_connect+0x879/0x1160
  tcp_v6_connect+0x50c/0x870
  mptcp_connect+0x129/0x280
  __inet_stream_connect+0xce/0x370
  inet_stream_connect+0x36/0x50
  bpf_trampoline_6442491565+0x49/0xef
  inet_stream_connect+0x5/0x50
  __sys_connect+0x63/0x90
  __x64_sys_connect+0x14/0x20

The root cause of the issue is that bpf allows accessing mptcp-level
proto_ops from a tcp subflow scope.

Fix the issue detecting the problematic call and preventing any action.

## Which versions are affected by CVE-2024-35894?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-35894?

Apply the vendor's patch.

## Is CVE-2024-35894 being exploited?

There is no known exploitation of CVE-2024-35894 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-2024-35894 and fix it if it is affected.

What it is: CVE-2024-35894 is a high-severity vulnerability in Linux kernel, published on 19 May 2024. 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-2024-35894 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-2024-35894/ (Markdown: https://insights.sbomify.com/CVE-2024-35894/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-35894
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-35894
- OSV: https://osv.dev/vulnerability/CVE-2024-35894

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-35894/
Summaries are generated and may contain mistakes; the official description above is the record.