{"id":"CVE-2026-98554","published":"2026-10-18T16:17:07.490","lastModified":"2026-10-19T10:19:11.773","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: ensure sufficient headroom in vlan_dev_hard_header()\n\nCallers that only reserve ETH_HLEN or less (such as llc_alloc_frame()),\nor skbs allocated before dynamic device/headroom changes (e.g. toggling\nVLAN_FLAG_REORDER_HDR or bonding/team switching slaves), can reach\nvlan_dev_hard_header() with insufficient headroom and trigger\nskb_under_panic().\n\nUse skb_cow_head() in vlan_dev_hard_header() when VLAN_FLAG_REORDER_HDR\nis not set to ensure sufficient headroom for the VLAN header(s) and the\nunderlying device hard header.\n\nUse READ_ONCE() to read dev->hard_header_len and dev->needed_headroom as\nthey can be updated concurrently under RTNL (e.g. in\nvlan_transfer_features()) while vlan_dev_hard_header() runs locklessly on\nthe transmit path. Also avoid LL_RESERVED_SPACE(dev) here so that the\nextra HH_DATA_MOD alignment padding does not trigger unnecessary\npskb_expand_head() reallocations on inner stacked VLAN devices after the\nouter VLAN header has been pushed.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/4ba1f57313f36a3ce6f77d593548f0c511f34aa1","tags":[]},{"url":"https://git.kernel.org/stable/c/55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b","tags":[]},{"url":"https://git.kernel.org/stable/c/5aca8e6a8ff6aeae358c1d9b65447aac416ace95","tags":[]},{"url":"https://git.kernel.org/stable/c/90d51095371d96747f45bbd8504edf6513e039ef","tags":[]},{"url":"https://git.kernel.org/stable/c/c7ee4bea64f559ea8e03260014775b64c720cb5b","tags":[]},{"url":"https://git.kernel.org/stable/c/ca797491f0ae4bfde9039f79f6f1ed7781c9110f","tags":[]},{"url":"https://git.kernel.org/stable/c/cd5dd68267c4238795fadaf02b3575ca3f8a6500","tags":[]},{"url":"https://git.kernel.org/stable/c/cfba0f45553de2b803059e3d539a1e418df24da8","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}