CVE-2026-43057

net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback

State: Published
Severity: 7.5 High
Published: May 1, 2026
Updated: Oct 15, 2026
Reserved: May 1, 2026

Description

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

net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback

NETIF_F_IPV6_CSUM only advertises support for checksum offload of packets without IPv6 extension headers. Packets with extension headers must fall back onto software checksumming. Since TSO depends on checksum offload, those must revert to GSO.

The below commit introduces that fallback. It always checks network header length. For tunneled packets, the inner header length must be checked instead. Extend the check accordingly.

A special case is tunneled packets without inner IP protocol. Such as RFC 6951 SCTP in UDP. Those are not standard IPv6 followed by transport header either, so also must revert to the software GSO path.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	a0478d7e888028f85fa7785ea838ce0ca09398e2 to before 2094a7cf91b71367b649f991aacc7b579f793d0bAffected 2156d9e9f2e483c8c3906c0ea57ea312c1424235 to before ed71cf465c75f5688b07a35d373cd1d6b589c8eaAffected 041e2f945f82fdbd6fff577b79c33469430297aa to before 33670f780e0120c3dacda188c512bbffe0b6044cAffected 864e3396976ef41de6cc7bc366276bf4e084fff2 to before a98b78116a27e2a57b696b569b2cb431c95cf9b6Affected 864e3396976ef41de6cc7bc366276bf4e084fff2 to before 732fdeb2987c94b439d51f5cb9addddc2fc48c42Affected 864e3396976ef41de6cc7bc366276bf4e084fff2 to before c4336a07eb6b2526dc2b62928b5104b41a7f81f5Affected 794ddbb7b63b6828c75967b9bcd43b086716e7a1Affected 6.1.149 to before 6.1.168Affected 6.6.103 to before 6.6.134Affected 6.12.44 to before 6.12.81Affected 6.16.4 to before 6.17Affected
LinuxLinux	6.17Affected before 6.17Not affected 6.1.168 through 6.1.Not affected 6.6.134 through 6.6.Not affected 6.12.81 through 6.12.Not affected 6.18.22 through 6.18.Not affected 6.19.12 through 6.19.*Not affected 7.0 and laterNot affected

Product

Versions

LinuxLinux

a0478d7e888028f85fa7785ea838ce0ca09398e2 to before 2094a7cf91b71367b649f991aacc7b579f793d0bAffected
2156d9e9f2e483c8c3906c0ea57ea312c1424235 to before ed71cf465c75f5688b07a35d373cd1d6b589c8eaAffected
041e2f945f82fdbd6fff577b79c33469430297aa to before 33670f780e0120c3dacda188c512bbffe0b6044cAffected
864e3396976ef41de6cc7bc366276bf4e084fff2 to before a98b78116a27e2a57b696b569b2cb431c95cf9b6Affected
864e3396976ef41de6cc7bc366276bf4e084fff2 to before 732fdeb2987c94b439d51f5cb9addddc2fc48c42Affected
864e3396976ef41de6cc7bc366276bf4e084fff2 to before c4336a07eb6b2526dc2b62928b5104b41a7f81f5Affected
794ddbb7b63b6828c75967b9bcd43b086716e7a1Affected
6.1.149 to before 6.1.168Affected
6.6.103 to before 6.6.134Affected
6.12.44 to before 6.12.81Affected
6.16.4 to before 6.17Affected

LinuxLinux

6.17Affected
before 6.17Not affected
6.1.168 through 6.1.*Not affected
6.6.134 through 6.6.*Not affected
6.12.81 through 6.12.*Not affected
6.18.22 through 6.18.*Not affected
6.19.12 through 6.19.*Not affected
7.0 and laterNot affected

References

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