CVE-2026-98554
Received
Received - Intake
VLAN Header Handling Flaw in Linux Kernel
Vulnerability report for CVE-2026-98554, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-18
Last updated on: 2026-10-18
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
vlan: ensure sufficient headroom in vlan_dev_hard_header()
Callers that only reserve ETH_HLEN or less (such as llc_alloc_frame()),
or skbs allocated before dynamic device/headroom changes (e.g. toggling
VLAN_FLAG_REORDER_HDR or bonding/team switching slaves), can reach
vlan_dev_hard_header() with insufficient headroom and trigger
skb_under_panic().
Use skb_cow_head() in vlan_dev_hard_header() when VLAN_FLAG_REORDER_HDR
is not set to ensure sufficient headroom for the VLAN header(s) and the
underlying device hard header.
Use READ_ONCE() to read dev->hard_header_len and dev->needed_headroom as
they can be updated concurrently under RTNL (e.g. in
vlan_transfer_features()) while vlan_dev_hard_header() runs locklessly on
the transmit path. Also avoid LL_RESERVED_SPACE(dev) here so that the
extra HH_DATA_MOD alignment padding does not trigger unnecessary
pskb_expand_head() reallocations on inner stacked VLAN devices after the
outer VLAN header has been pushed.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 2.6.12 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
