# CVE-2026-64055: net: ethernet: cortina: Carry over frag counter

> A logic error in the Cortina Ethernet driver resets the fragment counter prematurely, potentially causing packet assembly failures and denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-64055, DEBIAN-CVE-2026-64055, GHSA-j6pg-f87q-4363, UBUNTU-CVE-2026-64055

## What is CVE-2026-64055?

CVE-2026-64055 is a critical vulnerability in Linux kernel, published on 19 Jul 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: ethernet: cortina: Carry over frag counter

The gmac_rx() NAPI poll function assembles packets in an
SKB from a ring buffer.

If the ring buffer gets completely emptied during a poll cycle,
we exit gmac_rx(), but the packet is not yet completely
assembled in the SKB, yet the fragment counter frag_nr is
reset to zero on the next invocation.

Solve this by making the RX fragment counter a part of the
port struct, and carry it over between invocations.

Reset the fragment counter only right after calling
napi_gro_frags(), on error (after calling napi_free_frags())
or if stopping the port.

Reset it in some place where not strictly necessary just to
emphasize what is going on.

This was found by Sashiko during normal patch review.

## Which versions are affected by CVE-2026-64055?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64055?

Apply the vendor's patch.

## Is CVE-2026-64055 being exploited?

There is no known exploitation of CVE-2026-64055 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64055 and fix it if it is affected.

What it is: CVE-2026-64055 is a critical vulnerability in Linux kernel, published on 19 Jul 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-2026-64055 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-64055/ (Markdown: https://insights.sbomify.com/CVE-2026-64055/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64055
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64055
- OSV: https://osv.dev/vulnerability/CVE-2026-64055

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64055/
Summaries are generated and may contain mistakes; the official description above is the record.