# CVE-2026-99066: can: dev: init_can_skb(): restore skb header initialization


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-99066, GHSA-4qj9-2gm5-pxqj, UBUNTU-CVE-2026-99066

## What is CVE-2026-99066?

CVE-2026-99066 is a vulnerability in Linux, published on 23 Oct 2026. 

### Official description

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

can: dev: init_can_skb(): restore skb header initialization

Commit 9f10374bb024 ("can: remove private CAN skb headroom infrastructure")
removed the skb_reset_mac_header()/skb_reset_network_header()/
skb_reset_transport_header() calls from init_can_skb(). As a result, RX
skbs from alloc_can_skb() and friends again carry mac_header = 0xFFFF.
When such an skb reaches packet_rcv_spkt() (SOCK_PACKET), the push length
calculation overflows and triggers skb_under_panic -> kernel BUG -> full
machine panic.

The same issue was originally reported in 2014 on linux-can and fixed by
commit 969439016d2c ("can: add missing initialisations in CAN related
skbuffs"). packet_rcv_spkt() itself has never been hardened: only
packet_rcv() and tpacket_rcv() gained dev_has_header() checks in
commit d549699048b4 ("net/packet: fix packet receive on L3 devices
without visible hard header").

## Which versions are affected by CVE-2026-99066?


## How do I fix CVE-2026-99066?

Upgrade to a fixed version.

## Is CVE-2026-99066 being exploited?

There is no known exploitation of CVE-2026-99066 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99066 and fix it if it is affected.

What it is: CVE-2026-99066 is a vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99066 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-2026-99066/ (Markdown: https://insights.sbomify.com/CVE-2026-99066/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99066
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99066
- OSV: https://osv.dev/vulnerability/CVE-2026-99066

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99066/
Summaries are generated and may contain mistakes; the official description above is the record.