CVE-2026-99033: In the Linux kernel, the following vulnerability has been resolved: net/packet: guard the ll header push in packet_rcv_spkt() packet_rcv

In the Linux kernel, the following vulnerability has been resolved: net/packet: guard the ll header push in packet_rcv_spkt() packet_rcv_spkt() restores the l

In the Linux kernel, the following vulnerability has been resolved: net/packet: guard the ll header push in packet_rcv_spkt() packet_rcv_spkt() restores the link layer header with skb_push(skb, skb->data - skb_mac_header(skb)); That subtraction is only meaningful when the device actually has a link layer header. packet_rcv() and tpacket_rcv() both wrap it in dev_has_header(), which is also the predicate the block comment at the top of the file states the restore in terms of; packet_rcv_spkt() does not. commit d549699048b4 ("net/packet: fix packet receive on L3 devices without visible hard header") introduced the helper and changed the two call sites, and this one stayed behind. A device without a visible ll header can leave skb->mac_header at the 0xFFFF sentinel that __alloc_skb() initialises it to. A CAN skb does: init_can_skb() sets pkt_type and ip_summed but does not reset the headers, and commit 9f10374bb024 ("can: remove private CAN skb headroom infrastructure") dropped the skb_reset_*_header() calls that used to be there. skb_mac_header() is then 0xFFFF, the length becomes a large negative number and skb_push() reports it through skb_under_panic() -- from softirq co

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.18%, higher than 7% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 28, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

Weekly security brief

The flaws that hit local websites, every Friday.

One short email: what got exploited this week, which WordPress plugins broke, and what to check. Unsubscribe in one click.