CVE-2026-31684

Summary

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.

Impact & exploitability

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products we track (1)

Recommendation

Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/3d165d975305cf76ff0b10a3c798fb31e5f5f9a5 ↗

Additional information

• NVD record
• https://git.kernel.org/stable/c/3d165d975305cf76ff0b10a3c798fb31e5f5f9a5Patch
• https://git.kernel.org/stable/c/a69738efea0996d05a3c7d2178551b891744df1bPatch
• https://git.kernel.org/stable/c/c842743d073bdd683606cb414eb0ca84465dd834Patch
• https://git.kernel.org/stable/c/eb3765b90eb8f2a3d6310a80c14a9e57ec4267a2Patch
• https://git.kernel.org/stable/c/ec4930979b3f7bbeb7af5744599fc6603a4dba62Patch
• https://git.kernel.org/stable/c/0410c619e86551677fb79887a38eccad3f5a0725
• https://git.kernel.org/stable/c/46c07ad50fa2f4ba7663ee1b72b75ad7ad45cf09
• https://git.kernel.org/stable/c/886469b6455611a511aa6013e957e15e50577513