What’s Vulnerable › Vulnerabilities

CVE-2026-23154: net: fix segmentation of forwarding fraglist GRO

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-14 · updated 2026-10-19
• Weakness: CWE-20

Description

In the Linux kernel, the following vulnerability has been resolved: net: fix segmentation of forwarding fraglist GRO This patch enhances GSO segment handling by properly checking the SKB_GSO_DODGY flag for frag_list GSO packets, addressing low throughput issues observed when a station accesses IPv4 servers via hotspots with an IPv6-only upstream interface. Specifically, it fixes a bug in GSO segmentation when forwarding GRO packets containing a frag_list. The function skb_segment_list cannot correctly process GRO skbs that have been converted by XLAT, since XLAT only translates the header of the head skb. Consequently, skbs in the frag_list may remain untranslated, resulting in protocol inconsistencies and reduced throughput. To address this, the patch explicitly sets the SKB_GSO_DODGY flag for GSO packets in XLAT's IPv4/IPv6 protocol translation helpers (bpf_skb_proto_4_to_6 and bpf_skb_proto_6_to_4). This marks GSO packets as potentially modified after protocol translation. As a result, GSO segmentation will avoid using skb_segment_list and instead falls back to skb_segment for packets with the SKB_GSO_DODGY flag. This ensures that only safe and fully translated frag_list packets are processed by skb_segment_list, resolving protocol inconsistencies and improving throughput when forwarding GRO packets converted by XLAT.

Affected products

• Linux kernel: from 5.6 before 6.12.69; from 6.13 before 6.18.9; 6.19-rc1, 6.19-rc2, 6.19-rc3, 6.19-rc4, 6.19-rc5, 6.19-rc6 (+1) — fixed in 6.12.69, 6.18.9

How to fix

Upgrade to a fixed version: Linux kernel 6.12.69, 6.18.9. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/2cbef9ea5a0ac51863ede35c45f26931a85d3888
• https://git.kernel.org/stable/c/3d48d59235c494d34e32052f768393111c0806ef
• https://git.kernel.org/stable/c/3e62db1e3140449608975e29e0979cc5f3b1cc07
• https://git.kernel.org/stable/c/426ca15c7f6cb6562a081341ca88893a50c59fa2
• https://git.kernel.org/stable/c/9122d7280b2303e835cdfec156bd932ac1f586ed
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-082556.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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