# CVE-2026-99192: net: bcmgenet: unshare the skb before writing the control block


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** AZL-111359, BELL-CVE-2026-99192, DEBIAN-CVE-2026-99192, GHSA-gcjx-rww2-6xmm, UBUNTU-CVE-2026-99192

## What is CVE-2026-99192?

CVE-2026-99192 is a vulnerability in Linux, published on 28 Oct 2026. 

### Official description

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

net: bcmgenet: unshare the skb before writing the control block

bcmgenet stores first_cb, last_cb and bytes_sent in the skb control
block and reads them back on completion to free the skb and credit BQL.
ether_setup() leaves IFF_TX_SKB_SHARING set, so the stack can resubmit
a shared skb that is still in the ring. The next transmit overwrites
last_cb, so the earlier slots complete without crediting their bytes
and BQL stalls the queue until the watchdog resets it.

Unshare the skb before writing the control block.

Reproduce with pktgen in clone_skb mode, which hands the driver the same
skb while earlier copies are still in the ring:

  modprobe pktgen
  pg=/proc/net/pktgen
  echo "add_device eth0" > $pg/kpktgend_0
  echo "dst_mac AA:BB:CC:DD:EE:FF" > $pg/eth0
  echo "dst 192.0.2.1" > $pg/eth0
  echo "clone_skb 8" > $pg/eth0
  echo "count 0" > $pg/eth0
  echo start > $pg/pgctrl &
  sleep 5
  echo stop > $pg/pgctrl
  wait
  cat /sys/class/net/eth0/queues/tx-0/byte_queue_limits/inflight

inflight stays nonzero on the now idle queue. clone_skb 0 leaves it at
zero.

## Which versions are affected by CVE-2026-99192?


## How do I fix CVE-2026-99192?

Upgrade to a fixed version.

## Is CVE-2026-99192 being exploited?

There is no known exploitation of CVE-2026-99192 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99192 and fix it if it is affected.

What it is: CVE-2026-99192 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99192 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-2026-99192/ (Markdown: https://insights.sbomify.com/CVE-2026-99192/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99192
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99192
- OSV: https://osv.dev/vulnerability/CVE-2026-99192

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99192/
Summaries are generated and may contain mistakes; the official description above is the record.