CVE-2025-40078 Affecting linux-6.1 package, versions <6.1.158-1~deb11u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.03% (9th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-14114866
  • published26 Nov 2025
  • disclosed28 Oct 2025

Introduced: 28 Oct 2025

CVE-2025-40078  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.158-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1