CVE-2026-72407 geneve: validate inner network offset in geneve_gro_complete()
A race condition in the Linux kernel's Geneve GRO implementation allows out-of-bounds memory access, potentially leading to code execution or system crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72407?
CVE-2026-72407 is a critical memory corruption vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
geneve: validate inner network offset in geneve_gro_complete()
Even with both paths gated on gs->gro_hint, geneve_gro_complete() re-derives the inner dispatch type and length from the packet and the current gs->gro_hint, independently of geneve_gro_receive(). The two can disagree if gs->gro_hint flips under a concurrent geneve_quiesce()/ geneve_unquiesce() (sk_user_data is NULL across a synchronize_net()), or if the re-read option bytes differ from the ones receive parsed.
geneve_gro_receive() already records the inner network header position in NAPI_GRO_CB()->inner_network_offset. Have geneve_gro_complete() compute the offset it is about to dispatch at, adding ETH_HLEN in the ETH_P_TEB case where eth_gro_complete() steps over the inner MAC header, and bail out if it lands past inner_network_offset.
Use a lower bound rather than exact equality: between gh_len and the inner L3 header, geneve_gro_receive() may also have pulled an inner VLAN tag (vlan_gro_receive() advances the recorded offset past it), which only moves inner_network_offset further out. A valid frame therefore always satisfies inner_nh <= inner_network_offset, while a gh_len inflated by a hint gro_receive() did not honour dispatches past the validated inner header, i.e. the out-of-bounds completion. Only the latter is rejected.
Which versions are affected by CVE-2026-72407?
How do I fix CVE-2026-72407?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-72407 being exploited?
There is no known exploitation of CVE-2026-72407 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-72407, GHSA-gp9v-9c23-fw32, UBUNTU-CVE-2026-72407.