# CVE-2026-98288: net: stmmac: fix TSO header length truncation

> A remote attacker can cause a denial of service in the Linux kernel stmmac driver by sending crafted TCP packets with large IPv6 headers, triggering an integer overflow.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106452, BELL-CVE-2026-98288, DEBIAN-CVE-2026-98288, GHSA-gg98-59cc-cfq6, UBUNTU-CVE-2026-98288

## What is CVE-2026-98288?

CVE-2026-98288 is a vulnerability in Linux, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

net: stmmac: fix TSO header length truncation

stmmac_tso_xmit() stores the protocol header length returned by
stmmac_tso_header_size() in a u8. stmmac_tso_valid_packet() admits
headers up to 1023 bytes, so a header longer than 255 bytes wraps modulo
256 (486 becomes 230, 256 becomes 0).

A TCP over IPv6 socket carrying a few hundred bytes of sticky
destination/hop-by-hop options makes skb_tcp_all_headers() exceed 255
while staying below the 1023-byte limit, so such an skb reaches
stmmac_tso_xmit().

Widen proto_hdr_len to unsigned int, which is sufficient since the value
is bounded by the hardware limit, and adjust the debug print specifier
accordingly.

## Which versions are affected by CVE-2026-98288?


## How do I fix CVE-2026-98288?

Apply the vendor's patch.

## Is CVE-2026-98288 being exploited?

There is no known exploitation of CVE-2026-98288 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98288 and fix it if it is affected.

What it is: CVE-2026-98288 is a vulnerability in Linux, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98288 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-2026-98288/ (Markdown: https://insights.sbomify.com/CVE-2026-98288/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98288
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98288
- OSV: https://osv.dev/vulnerability/CVE-2026-98288

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98288/
Summaries are generated and may contain mistakes; the official description above is the record.