---
id: "CVE-2026-98557"
kind: "vulnerability"
aliases: ["CVE-2026-98557"]
title: "Linux kernel gve driver: wrong header length for UDP GSO packets"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["google-compute-engine", "gve-driver", "linux-kernel", "runtime"]
not_affected_if: ["no-gve-driver"]
published_at: "2026-10-18T16:17:07+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:23:26+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98557", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel gve driver: wrong header length for UDP GSO packets

The gve network driver in the Linux kernel computes header length with the TCP header rule even for UDP GSO packets, so segment buffer counts can be wrong. The sources describe a wrong-size header causing either needless GSO disabling or a packet whose segments exceed the driver's descriptor limit.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- Update to a Linux kernel release that includes the upstream commit fixing gve_can_send_tso() for SKB_GSO_UDP_L4 packets (the sources do not list fixed versions).

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98557

## From the sources

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

gve: DQO: fix header length used by gve_can_send_tso() for UDP GSO

gve_can_send_tso() computes how many buffers each segment of a GSO
packet would span, and for this it needs the length of the headers
that the device replicates in front of every segment.

It unconditionally uses skb_tcp_all_headers(), which reads the doff
field of the TCP header. SKB_GSO_UDP_L4 packets have no TCP header:
tcp_hdrlen() then reads one byte of the UDP payload, and header_len
can be anything in [0, 60] instead of the transport offset plus the
eight bytes of the UDP header that gve_prep_tso() programs into the
TSO context descriptor.

A wrong header length shifts all the segment boundaries computed in
the loop, so the number of buffers per segment can be over or under
estimated. In the first case, GSO is needlessly disabled for this
packet by gve_features_check_dqo() and the stack has to segment it.
In the second case, the driver hands the device a packet whose
segments span more than GVE_TX_MAX_DATA_DESCS buffers.

Use the UDP header length for SKB_GSO_UDP_L4 packets, matching what
gve_prep_tso() does.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_