# CVE-2025-40078

## Summary

- **CVE ID:** CVE-2025-40078
- **Severity:** UNKNOWN
- **CVSS Score:** 1.01
- **CWE:** N/A
- **Published:** Oct 28, 2025
- **Last Modified:** Sep 17, 2026

## 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.

## Affected Products

- Linux — Linux (1cedee13d25ab118d325f95588c1a084e9317229)
- Linux — Linux (4.18)
- Linux — Linux (0)
- Linux — Linux (5.4.301)
- Linux — Linux (5.10.246)
- Linux — Linux (5.15.195)
- Linux — Linux (6.1.156)
- Linux — Linux (6.6.112)
- Linux — Linux (6.12.53)
- Linux — Linux (6.17.3)
- Linux — Linux (6.18)

## References

- [CNA](https://git.kernel.org/stable/c/de44cdc50d2dce8718cb57deddf9cf1be9a7759f)
- [CNA](https://git.kernel.org/stable/c/76e04bbb4296fb6eac084dbfc27e02ccc744db3e)
- [CNA](https://git.kernel.org/stable/c/6d8b1a21fd5c34622b0c3893c61e4a38d8ba53ec)
- [CNA](https://git.kernel.org/stable/c/4f00858cd9bbbdf67159e28b85a8ca9e77c83622)
- [CNA](https://git.kernel.org/stable/c/cdeafacb4f9ff261a96baef519e29480fd7b1019)
- [CNA](https://git.kernel.org/stable/c/fe9d33f0470350558cb08cecb54cf2267b3a45d2)
- [CNA](https://git.kernel.org/stable/c/ad8b4fe5617e3c85fc23267f02500c4f3bf0ff69)
- [CNA](https://git.kernel.org/stable/c/6fabca2fc94d33cdf7ec102058983b086293395f)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.22%
- **EPSS Percentile:** 13.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._