{"id":"CVE-2026-98554","title":"vlan: ensure sufficient headroom in vlan_dev_hard_header()","summary":"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 dev…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5aca8e6a8ff6aeae358c1d9b65447aac416ace95","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 4ba1f57313f36a3ce6f77d593548f0c511f34aa1","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ca797491f0ae4bfde9039f79f6f1ed7781c9110f","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cfba0f45553de2b803059e3d539a1e418df24da8","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c7ee4bea64f559ea8e03260014775b64c720cb5b","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 90d51095371d96747f45bbd8504edf6513e039ef","Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cd5dd68267c4238795fadaf02b3575ca3f8a6500","Linux 2.6.12"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:18:21.751Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98554","references":[{"url":"https://git.kernel.org/stable/c/55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b"},{"url":"https://git.kernel.org/stable/c/5aca8e6a8ff6aeae358c1d9b65447aac416ace95"},{"url":"https://git.kernel.org/stable/c/4ba1f57313f36a3ce6f77d593548f0c511f34aa1"},{"url":"https://git.kernel.org/stable/c/ca797491f0ae4bfde9039f79f6f1ed7781c9110f"},{"url":"https://git.kernel.org/stable/c/cfba0f45553de2b803059e3d539a1e418df24da8"},{"url":"https://git.kernel.org/stable/c/c7ee4bea64f559ea8e03260014775b64c720cb5b"},{"url":"https://git.kernel.org/stable/c/90d51095371d96747f45bbd8504edf6513e039ef"},{"url":"https://git.kernel.org/stable/c/cd5dd68267c4238795fadaf02b3575ca3f8a6500"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.264Z","slug":"CVE-2026-98554","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 5aca8e6a8ff6aeae358c1d9b65447aac416ace95`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 4ba1f57313f36a3ce6f77d593548f0c511f34aa1`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ca797491f0ae4bfde9039f79f6f1ed7781c9110f`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cfba0f45553de2b803059e3d539a1e418df24da8`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c7ee4bea64f559ea8e03260014775b64c720cb5b`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 90d51095371d96747f45bbd8504edf6513e039ef`\n- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cd5dd68267c4238795fadaf02b3575ca3f8a6500`\n- `Linux 2.6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}