CVE-2026-99211

In the Linux kernel, the following vulnerability has been resolved:

netlink: reset skb headers before unicast and multicast filtering

Socket filters can use SKF NET OFF and SKF LL OFF to read relative to an skb's network and MAC headers. Netlink producers may reserve headroom without resetting those headers, allowing a receiving socket's filter to read data before the initialized message.

For example, IWPM HELLO replies are allocated with dev alloc skb(), which reserves NET SKB PAD bytes. An unprivileged NETLINK RDMA user can attach a classic socket filter and disclose this headroom through the length of the delivered reply. The resets in netlink dump() do not help because IWPM sends a separately allocated skb through netlink unicast().

Reset both headers before running the receiver's filter in unicast and broadcast delivery, as is already done for dump skbs. This also covers other netlink producers that reserve headroom without changing their allocation or message-building code.