# CVE-2026-98379: netfilter: ip6t_rpfilter: reject routes without inet6_dev

> An unprivileged user can trigger a kernel panic via IPv6 rpfilter lookup by manipulating network namespaces and MTU settings.

- **Severity:** Not scored
- **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:** 9 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106917, BELL-CVE-2026-98379, DEBIAN-CVE-2026-98379, GHSA-pm3c-rj84-8w7w, UBUNTU-CVE-2026-98379

## What is CVE-2026-98379?

CVE-2026-98379 is a vulnerability in Linux, published on 9 Oct 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: ip6t_rpfilter: reject routes without inet6_dev

ip6_route_lookup() can return an error-free route whose rt6i_idev is
NULL. Lowering an external nexthop device's MTU below IPV6_MIN_MTU tears
down its inet6_dev while fib6_ifdown() leaves routes using nexthop objects
in the FIB. An unprivileged user can construct this state with rtnetlink
in a private user and network namespace, then trigger a NULL dereference
through an IPv6 rpfilter lookup:

  Oops: general protection fault, probably for non-canonical address
  0xdffffc0000000000
  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  RIP: rpfilter_mt (net/ipv6/netfilter/ip6t_rpfilter.c:75)
  Call Trace:
  ip6t_do_table (net/ipv6/netfilter/ip6_tables.c:316)
  nf_hook_slow (net/netfilter/core.c:619)
  ipv6_rcv (net/ipv6/ip6_input.c:351)
  __netif_receive_skb_one_core (net/core/dev.c:6216)
  process_backlog (net/core/dev.c:6680)
  __napi_poll (net/core/dev.c:7739)
  net_rx_action (net/core/dev.c:7959)
  handle_softirqs (kernel/softirq.c:622)
  do_softirq.part.0 (kernel/softirq.c:523)
  __local_bh_enable_ip (kernel/softirq.c:450)
  __dev_queue_xmit (net/core/dev.c:4913)
  packet_sendmsg (net/packet/af_packet.c:3139)
  __sys_sendto (net/socket.c:2252)
  __x64_sys_sendto (net/socket.c:2259)
  do_syscall_64 (arch/x86/entry/syscall_64.c:94)
  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
  Kernel panic - not syncing: Fatal exception in interrupt

Reject routes without an inet6_dev immediately after lookup. Such routes
are not eligible for reverse-path filtering, and the check protects all
later rt6i_idev dereferences.

## Which versions are affected by CVE-2026-98379?


## How do I fix CVE-2026-98379?

Apply the vendor's patch.

## Is CVE-2026-98379 being exploited?

There is no known exploitation of CVE-2026-98379 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98379 and fix it if it is affected.

What it is: CVE-2026-98379 is a vulnerability in Linux, published on 9 Oct 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-2026-98379 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-2026-98379/ (Markdown: https://insights.sbomify.com/CVE-2026-98379/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98379
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98379
- OSV: https://osv.dev/vulnerability/CVE-2026-98379

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98379/
Summaries are generated and may contain mistakes; the official description above is the record.