# CVE-2025-40078: bpf: Explicitly check accesses to bpf_sock_addr

> A missing validation check in the Linux kernel BPF subsystem allows local attackers to trigger a verifier bug and kernel warning, potentially causing a denial of service.

- **Severity:** Not scored
- **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:** 28 Oct 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-68840, BELL-CVE-2025-40078, DEBIAN-CVE-2025-40078, GHSA-rvq5-xw4g-6wj7, ROOT-OS-DEBIAN-11-CVE-2025-40078, ROOT-OS-DEBIAN-12-CVE-2025-40078, ROOT-OS-DEBIAN-13-CVE-2025-40078, ROOT-OS-UBUNTU-2204-CVE-2025-40078, ROOT-OS-UBUNTU-2404-CVE-2025-40078, UBUNTU-CVE-2025-40078

## What is CVE-2025-40078?

CVE-2025-40078 is a missing authorization vulnerability in Linux, published on 28 Oct 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: Explicitly check accesses to bpf_sock_addr

Syzkaller found a kernel warning on the following sock_addr program:

    0: r0 = 0
    1: r2 = *(u32 *)(r1 +60)
    2: exit

which triggers:

    verifier bug: error during ctx access conversion (0)

This is happening because offset 60 in bpf_sock_addr corresponds to an
implicit padding of 4 bytes, right after msg_src_ip4. Access to this
padding isn't rejected in sock_addr_is_valid_access and it thus later
fails to convert the access.

This patch fixes it by explicitly checking the various fields of
bpf_sock_addr in sock_addr_is_valid_access.

I checked the other ctx structures and is_valid_access functions and
didn't find any other similar cases. Other cases of (properly handled)
padding are covered in new tests in a subsequent patch.

## Which versions are affected by CVE-2025-40078?


## How do I fix CVE-2025-40078?

Apply the vendor's patch.

## Is CVE-2025-40078 being exploited?

There is no known exploitation of CVE-2025-40078 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40078 and fix it if it is affected.

What it is: CVE-2025-40078 is a missing authorization vulnerability in Linux, published on 28 Oct 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-2025-40078 in the wild and no public exploit code.

Affected product: Linux. 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-2025-40078/ (Markdown: https://insights.sbomify.com/CVE-2025-40078/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40078
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40078
- OSV: https://osv.dev/vulnerability/CVE-2025-40078

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40078/
Summaries are generated and may contain mistakes; the official description above is the record.