cvedb.io
CVE-2025-39770
MEDIUM · CVSS 5.5
EPSS exploitation probability: 0%
Published 2025-09-11T17:15:42.530 · Last modified 2026-06-17T09:18:26.710

Summary

In the Linux kernel, the following vulnerability has been resolved: net: gso: Forbid IPv6 TSO with extensions on devices with only IPV6_CSUM When performing Generic Segmentation Offload (GSO) on an IPv6 packet that contains extension headers, the kernel incorrectly requests checksum offload if the egress device only advertises NETIF_F_IPV6_CSUM feature, which has a strict contract: it supports checksum offload only for plain TCP or UDP over IPv6 and explicitly does not support packets with extension headers. The current GSO logic violates this contract by failing to disable the feature for packets with extension headers, such as those used in GREoIPv6 tunnels. This violation results in the device being asked to perform an operation it cannot support, leading to a `skb_warn_bad_offload`

Affected products

linux — linux_kernel

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.