# CVE-2026-31407: netfilter: conntrack: add missing netlink policy validations

> An attacker can trigger out-of-bounds memory access in the Linux kernel netfilter subsystem, potentially leading to information disclosure or system crashes.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **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 Apr 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-81866, BELL-CVE-2026-31407, DEBIAN-CVE-2026-31407, GHSA-cf8w-8g67-48gv, ROOT-OS-DEBIAN-11-CVE-2026-31407, ROOT-OS-DEBIAN-12-CVE-2026-31407, ROOT-OS-DEBIAN-13-CVE-2026-31407, ROOT-OS-UBUNTU-2204-CVE-2026-31407, ROOT-OS-UBUNTU-2404-CVE-2026-31407, UBUNTU-CVE-2026-31407

## What is CVE-2026-31407?

CVE-2026-31407 is a high-severity memory corruption vulnerability in Linux kernel, published on 6 Apr 2026. 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:

netfilter: conntrack: add missing netlink policy validations

Hyunwoo Kim reports out-of-bounds access in sctp and ctnetlink.

These attributes are used by the kernel without any validation.
Extend the netlink policies accordingly.

Quoting the reporter:
  nlattr_to_sctp() assigns the user-supplied CTA_PROTOINFO_SCTP_STATE
  value directly to ct->proto.sctp.state without checking that it is
  within the valid range. [..]

  and: ... with exp->dir = 100, the access at
  ct->master->tuplehash[100] reads 5600 bytes past the start of a
  320-byte nf_conn object, causing a slab-out-of-bounds read confirmed by
  UBSAN.

Weakness: CWE-787 (Out-of-bounds Write), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-31407?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31407?

Apply the vendor's patch.

## Is CVE-2026-31407 being exploited?

There is no known exploitation of CVE-2026-31407 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-2026-31407 and fix it if it is affected.

What it is: CVE-2026-31407 is a high-severity memory corruption vulnerability in Linux kernel, published on 6 Apr 2026. 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-2026-31407 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-2026-31407/ (Markdown: https://insights.sbomify.com/CVE-2026-31407/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31407
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31407
- OSV: https://osv.dev/vulnerability/CVE-2026-31407

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31407/
Summaries are generated and may contain mistakes; the official description above is the record.