CVE-2026-31684

MEDIUM CVSS 3.1: 5.5 EPSS 0.12%
Updated Jun 17, 2026
Linux
Parameter Value
CVSS 5.5 (MEDIUM)
Affected Versions 4.19.99 — 7.0
Fixed In 6.12.83
Vendor Linux
Public PoC No

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.

Attack Parameters

Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Vulnerable Products 12

Configuration From (including) Up to (excluding)
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
5.1 6.12.83
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
5.1 6.18.24
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
5.1 6.19.14
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
5.1 7.0
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
4.19.99
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*
Linux Linux_Kernel
cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*