CVE-2026-31684 - net: sched: act_csum: validate nested VLAN headers

CVE-2026-31684 - net: sched: act_csum: validate nested VLAN headers

https://cvefeed.io/rssfeed/latest.atom / Sat, 04/25/2026 - 14:20
CVE ID :CVE-2026-31684
Published : April 25, 2026, 9:16 a.m. | 2 hours, 57 minutes ago
Description :In the Linux kernel, the following vulnerability has been resolved: net: sched: act_csum: validate nested VLAN headers tcf_csum_act() walks nested VLAN headers directly from skb->data when an skb still carries in-payload VLAN tags. The current code reads vlan->h_vlan_encapsulated_proto and then pulls VLAN_HLEN bytes without first ensuring that the full VLAN header is present in the linear area. If only part of an inner VLAN header is linearized, accessing h_vlan_encapsulated_proto reads past the linear area, and the following skb_pull(VLAN_HLEN) may violate skb invariants. Fix this by requiring pskb_may_pull(skb, VLAN_HLEN) before accessing and pulling each nested VLAN header. If the header still is not fully available, drop the packet through the existing error path.
Severity: 0.0 | NA
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