# CVE-2026-72348: netfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop

> Attackers can bypass ip6tables drop rules by sending malformed IPv6 extension headers, allowing unauthorized network traffic.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-72348, DEBIAN-CVE-2026-72348, GHSA-mf85-825j-jwwx, UBUNTU-CVE-2026-72348

## What is CVE-2026-72348?

CVE-2026-72348 is a critical vulnerability in Linux, published on 15 Aug 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: ip6tables: mark malformed IPv6 extension headers for hotdrop

The ah, hbh and rt matches check that the fixed extension header is
present, then use the header length field to derive the advertised
extension header length for matching.

For the ah match, add the missing advertised-length check. For hbh
and rt, update the existing advertised-length checks. In all three
cases, set hotdrop to true before returning false when the advertised
extension header length exceeds the available skb data.

Returning false treats the packet as a rule mismatch. Set hotdrop to
true and drop malformed packets so they cannot bypass rules intended
to drop packets with these IPv6 extension headers.

## Which versions are affected by CVE-2026-72348?


## How do I fix CVE-2026-72348?

Apply the vendor's patch.

## Is CVE-2026-72348 being exploited?

There is no known exploitation of CVE-2026-72348 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72348 and fix it if it is affected.

What it is: CVE-2026-72348 is a critical vulnerability in Linux, published on 15 Aug 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-2026-72348 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-2026-72348/ (Markdown: https://insights.sbomify.com/CVE-2026-72348/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72348
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72348
- OSV: https://osv.dev/vulnerability/CVE-2026-72348

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72348/
Summaries are generated and may contain mistakes; the official description above is the record.