{"id":"CVE-2026-90160","summary":"lwt_bpf: Restore reserved headroom after xmit program","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nlwt_bpf: Restore reserved headroom after xmit program\n\nip_finish_output2() expands an skb to LL_RESERVED_SPACE(dev) before LWT\nxmit. An LWT_XMIT BPF program can then modify the skb head and still\nreturn BPF_OK, so bpf_xmit() rechecks the remaining headroom before the\nskb continues to neighbour output.\n\nThat recheck uses dst-\u003edev-\u003ehard_header_len. This is not enough for the\nneighbour cached-header path: neigh_hh_output() copies the cached hardware\nheader using the aligned hh_cache size, HH_DATA_MOD for short headers or\nHH_DATA_ALIGN(hh_len) otherwise.\n\nOn Ethernet, hard_header_len is 14 but the cached copy needs 16 bytes. If\nan LWT_XMIT BPF program calls bpf_skb_change_head(skb, 1, 0), the skb can\nstill have 15 bytes of headroom after the program. The existing check\naccepts that, after which neigh_hh_output() hits its headroom warning and\ndrops the skb.\n\nUse LL_RESERVED_SPACE(dst-\u003edev) in the post-BPF headroom check to match\nthe reservation made before LWT xmit.","modified":"2026-09-19T03:47:24.857476301Z","published":"2026-09-17T16:06:51.806Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90160.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/179a5b2171573d94a25c9aa8e1c9f9ac352ad316"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5fe7007aed9ad069b2bd77e5d0c875c64f5c0269"},{"type":"WEB","url":"https://git.kernel.org/stable/c/753e5cdcca5474d230d62bb3489e5168ab27c272"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7cf561843ed0ad57501892a65abb77957e6c800f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7d043e24520a273c362be5dd7d9c82796879a49b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a38c0eb447e2dd0120a2ebcdba470f9505ac8907"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c488071c3441fa34f5a87cd6c12ce2cc6304f20e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/de2b2004e16f2930eb689175e2c1998b0a68d499"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90160.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90160"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2"},{"fixed":"753e5cdcca5474d230d62bb3489e5168ab27c272"},{"fixed":"c488071c3441fa34f5a87cd6c12ce2cc6304f20e"},{"fixed":"a38c0eb447e2dd0120a2ebcdba470f9505ac8907"},{"fixed":"de2b2004e16f2930eb689175e2c1998b0a68d499"},{"fixed":"7d043e24520a273c362be5dd7d9c82796879a49b"},{"fixed":"7cf561843ed0ad57501892a65abb77957e6c800f"},{"fixed":"179a5b2171573d94a25c9aa8e1c9f9ac352ad316"},{"fixed":"5fe7007aed9ad069b2bd77e5d0c875c64f5c0269"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90160.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.10.0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90160.json"}}],"schema_version":"1.9.0"}