High [CVE-2026-72408] gate GRO hint in geneve_gro_complete on gs->gro_hint
This high-severity Red Hat Linux advisory covers CVE-2026-72408 affecting Red Hat Enterprise Linux 10, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint geneve_gro_receive() reads the GRO hint through geneve_sk_gro_hint_off(), which honours it only when the socket enabled IFLA_GENEVE_GRO_HINT (gs->gro_hint). geneve_gro_complete() instead calls the low-level geneve_opt_gro_hint_off() and acts on the hint unconditionally.
On a tunnel without the hint, receive aggregates the frames as plain ETH_P_TEB while complete still honours an attacker-supplied hint option: it inflates gh_len by gro_hint->nested_hdr_len (u8) and redirects the dispatch type, so the inner gro_complete handler runs at nhoff + gh_len, an offset receive never pulled nor validated, reading out of bounds of the skb head: BUG: KASAN: slab-out-of-bounds in ipv6_gro_complete (net/ipv6/ip6_offload.c:196) Read of size 1 at addr ffff88800fe91980 by task exploit/153 ipv6_gro_complete (net/ipv6/ip6_offload.c:196) geneve_gro_complete (drivers/net/geneve.c:965) udp_gro_complete (net/ipv4/udp_offload.c:940) inet_gro_complete (net/ipv4/af_inet.c:1621) __gro_flush (net/core/gro.c:306) Gate the complete path on gs->gro_hint too via geneve_sk_gro_hint_off(), so both paths agree.
Tunnels that enable the hint are unaffected.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat package: kernel.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 55 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 55 minutes ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 55 minutes ago·verify at source
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