# CVE-2025-40278: net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak

> A local attacker can read uninitialized kernel memory via netlink messages due to improper initialization in the IFE action module.

- **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:** 6 Dec 2025
- **Updated:** 2 Jun 2026
- **Also known as:** BELL-CVE-2025-40278, DEBIAN-CVE-2025-40278, GHSA-8p8p-qx6g-jxw6, ROOT-OS-UBUNTU-2204-CVE-2025-40278, ROOT-OS-UBUNTU-2404-CVE-2025-40278, UBUNTU-CVE-2025-40278

## What is CVE-2025-40278?

CVE-2025-40278 is a vulnerability in Linux, published on 6 Dec 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:

net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak

Fix a KMSAN kernel-infoleak detected  by the syzbot .

[net?] KMSAN: kernel-infoleak in __skb_datagram_iter

In tcf_ife_dump(), the variable 'opt' was partially initialized using a
designatied initializer. While the padding bytes are reamined
uninitialized. nla_put() copies the entire structure into a
netlink message, these uninitialized bytes leaked to userspace.

Initialize the structure with memset before assigning its fields
to ensure all members and padding are cleared prior to beign copied.

This change silences the KMSAN report and prevents potential information
leaks from the kernel memory.

This fix has been tested and validated by syzbot. This patch closes the
bug reported at the following syzkaller link and ensures no infoleak.

## Which versions are affected by CVE-2025-40278?


## How do I fix CVE-2025-40278?

Apply the vendor's patch.

## Is CVE-2025-40278 being exploited?

There is no known exploitation of CVE-2025-40278 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40278 and fix it if it is affected.

What it is: CVE-2025-40278 is a vulnerability in Linux, published on 6 Dec 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-2025-40278 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-2025-40278/ (Markdown: https://insights.sbomify.com/CVE-2025-40278/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40278
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40278
- OSV: https://osv.dev/vulnerability/CVE-2025-40278

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40278/
Summaries are generated and may contain mistakes; the official description above is the record.