Linux kernel: Netlink skb headroom disclosure via unicast filter
CVE-2026-99211 Published on October 28, 2026
netlink: reset skb headers before unicast and multicast filtering
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.
Products Associated with CVE-2026-99211
Want to know whenever a new CVE is published for Linux Kernel? stack.watch will email you.
Affected Versions
Linux:- Version b1153f29ee07dc1a788964409255a4b4fae50b98 and below 06791594274f87c29f1a9f1961d700272716a49d is affected.
- Version b1153f29ee07dc1a788964409255a4b4fae50b98 and below 06935da5de83aa8b98841563894857e7d2f80e47 is affected.
- Version b1153f29ee07dc1a788964409255a4b4fae50b98 and below 8bf659bd54e1f00e34cf5244b1d289c506fa47c0 is affected.
- Version 2.6.26 is affected.
- Before 2.6.26 is unaffected.
- Version 6.18.59, <= 6.18.* is unaffected.
- Version 7.2.13, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.