# CVE-2026-52998: netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check

> A NULL pointer dereference in the Linux kernel netfilter module allows attackers to cause a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-52998, DEBIAN-CVE-2026-52998, GHSA-pphc-92v7-v4w2, ROOT-OS-DEBIAN-11-CVE-2026-52998, ROOT-OS-DEBIAN-12-CVE-2026-52998, ROOT-OS-UBUNTU-2204-CVE-2026-52998, ROOT-OS-UBUNTU-2404-CVE-2026-52998, UBUNTU-CVE-2026-52998

## What is CVE-2026-52998?

CVE-2026-52998 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check

The nf_osf_ttl() function accessed skb->dev to perform a local interface
address lookup without verifying that the device pointer was valid.

Additionally, the implementation utilized an in_dev_for_each_ifa_rcu
loop to match the packet source address against local interface
addresses. It assumed that packets from the same subnet should not see a
decrement on the initial TTL. A packet might appear it is from the same
subnet but it actually isn't especially in modern environments with
containers and virtual switching.

Remove the device dereference and interface loop. Replace the logic with
a switch statement that evaluates the TTL according to the ttl_check.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-52998?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52998?

Apply the vendor's patch.

## Is CVE-2026-52998 being exploited?

There is no known exploitation of CVE-2026-52998 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52998 and fix it if it is affected.

What it is: CVE-2026-52998 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-52998 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-52998/ (Markdown: https://insights.sbomify.com/CVE-2026-52998/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52998
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52998
- OSV: https://osv.dev/vulnerability/CVE-2026-52998

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52998/
Summaries are generated and may contain mistakes; the official description above is the record.