CVE-2026-98557 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux systems with the gve driver should be aware of this vulnerability. They should verify Linux kernel versions to ensure the fix is applied and assess exposure for systems using the gve driver to determine potential impact. Additionally, they should monitor for potential GSO issues that may arise from incorrect header length calculation.

Why it matters

A vulnerability in the Linux kernel's gve driver has been resolved, and defenders should verify Linux kernel versions and assess exposure for systems using the gve driver to determine potential impact.

• Verify Linux kernel versions to ensure the fix is applied
• Assess exposure for systems using the gve driver to determine potential impact
• Monitor for potential GSO issues that may arise from incorrect header length calculation

Technical summary

The gve_can_send_tso() function in the Linux kernel's gve driver incorrectly calculates the header length for UDP GSO packets, potentially leading to GSO disablement or device packet handling issues. This occurs because the function uses skb_tcp_all_headers(), which is not suitable for SKB_GSO_UDP_L4 packets lacking a TCP header. As a result, tcp_hdrlen() may read the UDP payload, causing incorrect header_len calculations. This miscalculation affects segment boundary determination, potentially causing GSO to be disabled unnecessarily or the driver to handle packets improperly.

Defensive priority

Verify Linux kernel versions and assess exposure for systems using the gve driver.

Recommended defensive actions

• Verify Linux kernel versions
• Assess exposure for systems using the gve driver
• Monitor for potential GSO issues
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions, retest remediated assets
• Plan vendor-supported updates or mitigations

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but do not specify affected or fixed versions. The Linux kernel's gve driver is impacted, and defenders should verify Linux kernel versions and assess exposure for systems using the gve driver. The vulnerability is resolved in the Linux kernel, and the fix involves using the correct header length for UDP GSO packets. Defenders should focus on verifying kernel versions and assessing potential impact on systems utilizing the gve driver.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.