CVE-2026-99211 netlink: reset skb headers before unicast and multicast filtering
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99211?
CVE-2026-99211 is a vulnerability in Linux, published on 28 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-99211?
How do I fix CVE-2026-99211?
Upgrade to a fixed version.
Is CVE-2026-99211 being exploited?
There is no known exploitation of CVE-2026-99211 in the wild and no public exploit code.
Sources
Also known as AZL-111374, BELL-CVE-2026-99211, DEBIAN-CVE-2026-99211, GHSA-rx9x-87v5-hrch, UBUNTU-CVE-2026-99211.