# CVE-2026-99073: ipv4: stop exception dump when nexthop group shrinks


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** BELL-CVE-2026-99073, DEBIAN-CVE-2026-99073, GHSA-4527-q5wc-xrv7, UBUNTU-CVE-2026-99073

## What is CVE-2026-99073?

CVE-2026-99073 is a vulnerability in Linux, published on 23 Oct 2026. 

### Official description

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

ipv4: stop exception dump when nexthop group shrinks

Commit 4ce5dc9316de ("inet: switch inet_dump_fib() to RCU
protection") allowed IPv4 FIB dumps to run concurrently with nexthop
replacement.

fib_dump_info_fnhe() uses fib_info_num_path() as the loop bound,
then fib_info_nhc() independently reloads nh->nh_grp. If
RTM_NEWNEXTHOP replaces a group with fewer paths between those loads,
fib_info_nhc() returns NULL and the dump dereferences it through
nhc_flags.

Stop the walk when the indexed path is absent. Nexthop groups are
dense, so the current snapshot has no later path.

## Which versions are affected by CVE-2026-99073?


## How do I fix CVE-2026-99073?

Upgrade to a fixed version.

## Is CVE-2026-99073 being exploited?

There is no known exploitation of CVE-2026-99073 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99073 and fix it if it is affected.

What it is: CVE-2026-99073 is a vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99073 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-2026-99073/ (Markdown: https://insights.sbomify.com/CVE-2026-99073/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99073
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99073
- OSV: https://osv.dev/vulnerability/CVE-2026-99073

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99073/
Summaries are generated and may contain mistakes; the official description above is the record.