# CVE-2026-63858: netfilter: nf_tables: add hook transactions for device deletions

> A race condition in Linux kernel netfilter hook deletion can disrupt RCU-protected list readers, potentially causing system instability or denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-92582, BELL-CVE-2026-63858, DEBIAN-CVE-2026-63858, GHSA-w348-qxhm-w5rx, ROOT-OS-DEBIAN-11-CVE-2026-63858, ROOT-OS-DEBIAN-12-CVE-2026-63858, ROOT-OS-DEBIAN-13-CVE-2026-63858, ROOT-OS-UBUNTU-2204-CVE-2026-63858, UBUNTU-CVE-2026-63858

## What is CVE-2026-63858?

CVE-2026-63858 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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: nf_tables: add hook transactions for device deletions

Restore the flag that indicates that the hook is going away, ie.
NFT_HOOK_REMOVE, but add a new transaction object to track deletion
of hooks without altering the basechain/flowtable hook_list during
the preparation phase.

The existing approach that moves the hook from the basechain/flowtable
hook_list to transaction hook_list breaks netlink dump path readers
of this RCU-protected list.

It should be possible use an array for nft_trans_hook to store the
deleted hooks to compact the representation but I am not expecting
many hook object, specially now that wildcard support for devices
is in place.

Note that the nft_trans_chain_hooks() list contains a list of struct
nft_trans_hook objects for DELCHAIN and DELFLOWTABLE commands, while
this list stores struct nft_hook objects for NEWCHAIN and NEWFLOWTABLE.
Note that new commands can be updated to use nft_trans_hook for
consistency.

This patch also adapts the event notification path to deal with the list
of hook transactions.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-63858?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-63858?

Apply the vendor's patch.

## Is CVE-2026-63858 being exploited?

There is no known exploitation of CVE-2026-63858 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-2026-63858 and fix it if it is affected.

What it is: CVE-2026-63858 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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-2026-63858 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-2026-63858/ (Markdown: https://insights.sbomify.com/CVE-2026-63858/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63858
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63858
- OSV: https://osv.dev/vulnerability/CVE-2026-63858

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63858/
Summaries are generated and may contain mistakes; the official description above is the record.