CVE-2026-72408: geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
In the Linux kernel, the following vulnerability has been resolved:
geneve: gate GRO hint in genevegrocomplete() on gs->grohint
genevegroreceive() reads the GRO hint through geneveskgrohintoff(), which honours it only when the socket enabled IFLAGENEVEGROHINT (gs->grohint). genevegrocomplete() instead calls the low-level geneveoptgrohintoff() and acts on the hint unconditionally.
On a tunnel without the hint, receive aggregates the frames as plain ETHPTEB while complete still honours an attacker-supplied hint option: it inflates ghlen by grohint->nestedhdrlen (u8) and redirects the dispatch type, so the inner grocomplete handler runs at nhoff + ghlen, an offset receive never pulled nor validated, reading out of bounds of the skb head:
BUG: KASAN: slab-out-of-bounds in ipv6grocomplete (net/ipv6/ip6offload.c:196) Read of size 1 at addr ffff88800fe91980 by task exploit/153 ipv6grocomplete (net/ipv6/ip6offload.c:196) genevegrocomplete (drivers/net/geneve.c:965) udpgrocomplete (net/ipv4/udpoffload.c:940) inetgrocomplete (net/ipv4/afinet.c:1621) groflush (net/core/gro.c:306)
Gate the complete path on gs->grohint too via geneveskgrohintoff(), so both paths agree. Tunnels that enable the hint are unaffected.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Configuration
Enable the Geneve GRO hint on the tunnel socket; tunnels with the hint enabled are unaffected.
Geneve tunnel IFLA_GENEVE_GRO_HINT = enabled
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72408?
CVE-2026-72408 has a risk rating of 60.
What components are affected by CVE-2026-72408?
CVE-2026-72408 affects the Linux kernel and specifically the geneve module.
How do I fix CVE-2026-72408?
To fix CVE-2026-72408, update your Linux kernel to the latest version that addresses this vulnerability.
What is the exploit impact of CVE-2026-72408?
CVE-2026-72408 may allow an attacker to manipulate GRO hint leading to potential data integrity issues.
Is there a workaround for CVE-2026-72408?
Currently, the recommended solution for CVE-2026-72408 is to apply the available kernel update.