# CVE-2026-89780: net: qualcomm: rmnet: restore skb->dev on deaggregated frames

> An unprivileged user can cause a kernel panic via null pointer dereference in the Qualcomm rmnet driver by sending crafted network frames.

- **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:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89780, DEBIAN-CVE-2026-89780, GHSA-2f6m-7f8f-p7hp, UBUNTU-CVE-2026-89780

## What is CVE-2026-89780?

CVE-2026-89780 is a vulnerability in Linux, published on 16 Sep 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:

net: qualcomm: rmnet: restore skb->dev on deaggregated frames

rmnet_map_deaggregate() allocates each sub-frame with alloc_skb() and
leaves skb->dev NULL. __rmnet_map_ingress_handler() assigns
skb->dev = ep->egress_dev only on the data path, but a MAP command frame
is dispatched to rmnet_map_command() before that, so rmnet_map_send_ack()
runs netif_tx_lock(skb->dev) on a NULL device. An unprivileged user
reaches this by unsharing a user+net namespace, creating an rmnet link
over a tap device with INGRESS_DEAGGREGATION and INGRESS_MAP_COMMANDS,
and writing an aggregated frame carrying a flow-control command to the
tap fd.

Restore the assignment dropped by 378e25357ac7, so every skb leaving
rmnet_map_deaggregate() has a valid device.

  BUG: KASAN: null-ptr-deref in _raw_spin_lock (kernel/locking/spinlock.c:158)
  Write of size 4 at addr 00000000000004b4 by task exploit/144
  Call Trace:
   _raw_spin_lock (kernel/locking/spinlock.c:158)
   netif_tx_lock (net/sched/sch_generic.c:497)
   rmnet_map_command (drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c:67)
   rmnet_rx_handler (drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c:125)
   __netif_receive_skb_core.constprop.0 (net/core/dev.c:6103)
   ...
   __netif_receive_skb_one_core (net/core/dev.c:6214)
   netif_receive_skb (net/core/dev.c:6474)
   tun_get_user (drivers/net/tun.c:1966)
   tun_chr_write_iter (drivers/net/tun.c:2012)
   vfs_write (fs/read_write.c:687)
   ksys_write (fs/read_write.c:739)
   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

## Which versions are affected by CVE-2026-89780?


## How do I fix CVE-2026-89780?

Apply the vendor's patch.

## Is CVE-2026-89780 being exploited?

There is no known exploitation of CVE-2026-89780 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89780 and fix it if it is affected.

What it is: CVE-2026-89780 is a vulnerability in Linux, published on 16 Sep 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-2026-89780 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-2026-89780/ (Markdown: https://insights.sbomify.com/CVE-2026-89780/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89780
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89780
- OSV: https://osv.dev/vulnerability/CVE-2026-89780

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89780/
Summaries are generated and may contain mistakes; the official description above is the record.