CVE-2026-99211

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.

Is your site exposed to CVE-2026-99211?

Run a free security scan — no signup, results in seconds.

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/06791594274f87c29f1a9f1961d700272716a49d https://git.kernel.org/stable/c/06935da5de83aa8b98841563894857e7d2f80e47 https://git.kernel.org/stable/c/4123f8d2099863e2421187af9d87b45e8eebd867 https://git.kernel.org/stable/c/6ec7cc02458c6a1509377a7f2eec9c7b1a355b5e https://git.kernel.org/stable/c/8bf659bd54e1f00e34cf5244b1d289c506fa47c0 https://git.kernel.org/stable/c/c69db9e1f5cf886d4e3011313761a0f63a1d0da0 https://git.kernel.org/stable/c/ea0e0fc4c72f71bd6d8bf460bfe309b61c35b548

Frequently Asked Questions

What is 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.

How do I check if I'm vulnerable to CVE-2026-99211? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.