# CVE-2026-43451: netfilter: nfnetlink_queue: fix entry leak in bridge verdict error path

> A memory leak in the Linux kernel netfilter bridge verdict path allows attackers to exhaust kernel memory, causing denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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:** 8 May 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-43451, DEBIAN-CVE-2026-43451, GHSA-hx98-q4r6-mgcv, ROOT-OS-DEBIAN-11-CVE-2026-43451, ROOT-OS-UBUNTU-2204-CVE-2026-43451, ROOT-OS-UBUNTU-2404-CVE-2026-43451, UBUNTU-CVE-2026-43451

## What is CVE-2026-43451?

CVE-2026-43451 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 May 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: nfnetlink_queue: fix entry leak in bridge verdict error path

nfqnl_recv_verdict() calls find_dequeue_entry() to remove the queue
entry from the queue data structures, taking ownership of the entry.
For PF_BRIDGE packets, it then calls nfqa_parse_bridge() to parse VLAN
attributes.  If nfqa_parse_bridge() returns an error (e.g. NFQA_VLAN
present but NFQA_VLAN_TCI missing), the function returns immediately
without freeing the dequeued entry or its sk_buff.

This leaks the nf_queue_entry, its associated sk_buff, and all held
references (net_device refcounts, struct net refcount).  Repeated
triggering exhausts kernel memory.

Fix this by dropping the entry via nfqnl_reinject() with NF_DROP verdict
on the error path, consistent with other error handling in this file.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-43451?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43451?

Apply the vendor's patch.

## Is CVE-2026-43451 being exploited?

There is no known exploitation of CVE-2026-43451 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-2026-43451 and fix it if it is affected.

What it is: CVE-2026-43451 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 May 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-2026-43451 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-2026-43451/ (Markdown: https://insights.sbomify.com/CVE-2026-43451/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43451
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43451
- OSV: https://osv.dev/vulnerability/CVE-2026-43451

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43451/
Summaries are generated and may contain mistakes; the official description above is the record.