CVE-2026-31684
5.5 · MEDIUMOverview
CVE-2026-31684 is a medium-severity vulnerability affecting linux linux_kernel. It was published on April 25, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linux | linux_kernel | >= 4.19.99, < 4.20 | Affected |
References
Frequently Asked Questions
What is CVE-2026-31684?
CVE-2026-31684 is a medium-severity vulnerability affecting linux linux_kernel. It was published on April 25, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2026-31684?
This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-31684?
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-31684?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-31684 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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