Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 4.19.99, < 4.20 |
References
- 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
FAQ
What is CVE-2026-31684?
CVE-2026-31684 is a vulnerability with a CVSS score of 5.5 (MEDIUM). 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 st...
How severe is CVE-2026-31684?
CVE-2026-31684 has been rated MEDIUM with a CVSS base score of 5.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-31684?
Check the references section above for vendor advisories and patch information. Affected products include: Linux Linux Kernel.