# CVE-2026-98850: net/packet: prevent TX_RING byte count overflow

> A local attacker with CAP_NET_RAW can trigger an integer overflow in the Linux kernel packet socket implementation, causing a kernel panic and denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-108860, BELL-CVE-2026-98850, DEBIAN-CVE-2026-98850, GHSA-prpm-w567-3rvc, UBUNTU-CVE-2026-98850

## What is CVE-2026-98850?

CVE-2026-98850 is a vulnerability in Linux, published on 18 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:

net/packet: prevent TX_RING byte count overflow

tpacket_snd() drains every SEND_REQUEST frame in a TX ring and adds
each valid packet length to the signed int len_sum. Userspace can
recycle completed frames concurrently, so a single blocking send call
is not bounded by the ring size.

After enough successful transmissions len_sum wraps into the negative
range. In particular, 65536 65535-byte frames followed by a 65007-byte
frame produce 0xfffffdef, or -EIOCBQUEUED. sock_sendmsg_nosec() treats
that as an impossible return and triggers a BUG. On systems configured
to panic on oops, a CAP_NET_RAW holder can panic the host kernel.

Stop before the next frame would make the byte count exceed INT_MAX.
The positive short count leaves that frame pending for a later send
call.

A two-thread TPACKET_V2 reproducer triggered the BUG on an arm64 build
of Linux 7.3-rc4. With this change, the same reproducer returned the
expected positive short count without an oops.

## Which versions are affected by CVE-2026-98850?


## How do I fix CVE-2026-98850?

Apply the vendor's patch.

## Is CVE-2026-98850 being exploited?

There is no known exploitation of CVE-2026-98850 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98850 and fix it if it is affected.

What it is: CVE-2026-98850 is a vulnerability in Linux, published on 18 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-2026-98850 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-2026-98850/ (Markdown: https://insights.sbomify.com/CVE-2026-98850/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98850
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98850
- OSV: https://osv.dev/vulnerability/CVE-2026-98850

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98850/
Summaries are generated and may contain mistakes; the official description above is the record.