CVE-2026-74701 net/openvswitch: check Ethernet header length in key_extract()
A missing length check in the Linux kernel's Open vSwitch module allows local attackers to trigger a kernel crash via crafted packets on TUN devices.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74701?
CVE-2026-74701 is a high-severity vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net/openvswitch: check Ethernet header length in key_extract()
When a packet arrives on an ARPHRD_NONE device (e.g. TUN), ovs_flow_key_extract() trusts the user-provided skb->protocol field: if it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes for MAC addresses and parse_ethertype() pulls 2 more, either of which triggers a kernel BUG in __skb_pull() when the linear area is too small.
kernel BUG at include/linux/skbuff.h:2848! RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933 ovs_flow_key_extract+0x419/0xa70 ovs_vport_receive+0x222/0x390 netdev_frame_hook+0x3e0/0x630 tun_get_user+0x2d0c/0x38e0
Fixed by calling check_header() in key_extract() before accessing the Ethernet header.
Which versions are affected by CVE-2026-74701?
How do I fix CVE-2026-74701?
Apply the vendor's patch.
Is CVE-2026-74701 being exploited?
There is no known exploitation of CVE-2026-74701 in the wild and no public exploit code.
Sources
Also known as AZL-97167, BELL-CVE-2026-74701, DEBIAN-CVE-2026-74701, GHSA-6727-4wmg-w3rc, UBUNTU-CVE-2026-74701.