CVE-2026-43057

CVE-2026-43057 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

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.

Frequently asked questions

What is CVE-2026-43057?
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.
How severe is CVE-2026-43057?
CVE-2026-43057 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-43057 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-43057?
CVE-2026-43057 primarily affects Linux Linux Kernel. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-43057?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-43057 have an EU (EUVD) identifier?
Yes. CVE-2026-43057 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26656.
When was CVE-2026-43057 published?
CVE-2026-43057 was published on 2026-05-01 and last updated on 2026-06-17.

References

Affected products (12)

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