{"id":"CVE-2026-90160","state":"PUBLISHED","title":"lwt_bpf: Restore reserved headroom after xmit program","description":"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->dev->hard_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->dev) in the post-BPF headroom check to match\nthe reservation made before LWT xmit.","publishedAt":"2026-09-17T16:06:51.806Z","updatedAt":"2026-10-19T08:58:58.842Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"753e5cdcca5474d230d62bb3489e5168ab27c272","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"c488071c3441fa34f5a87cd6c12ce2cc6304f20e","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"a38c0eb447e2dd0120a2ebcdba470f9505ac8907","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"de2b2004e16f2930eb689175e2c1998b0a68d499","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"7d043e24520a273c362be5dd7d9c82796879a49b","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"7cf561843ed0ad57501892a65abb77957e6c800f","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"179a5b2171573d94a25c9aa8e1c9f9ac352ad316","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"5fe7007aed9ad069b2bd77e5d0c875c64f5c0269","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/lwt_bpf.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.10","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/lwt_bpf.c"]}],"references":["https://git.kernel.org/stable/c/753e5cdcca5474d230d62bb3489e5168ab27c272","https://git.kernel.org/stable/c/c488071c3441fa34f5a87cd6c12ce2cc6304f20e","https://git.kernel.org/stable/c/a38c0eb447e2dd0120a2ebcdba470f9505ac8907","https://git.kernel.org/stable/c/de2b2004e16f2930eb689175e2c1998b0a68d499","https://git.kernel.org/stable/c/7d043e24520a273c362be5dd7d9c82796879a49b","https://git.kernel.org/stable/c/7cf561843ed0ad57501892a65abb77957e6c800f","https://git.kernel.org/stable/c/179a5b2171573d94a25c9aa8e1c9f9ac352ad316","https://git.kernel.org/stable/c/5fe7007aed9ad069b2bd77e5d0c875c64f5c0269"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90160.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90160","state":"PUBLISHED","datePublished":"2026-09-17T16:06:51.806Z","dateUpdated":"2026-10-19T08:58:58.842Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.790Z"},"containers":{"cna":{"title":"lwt_bpf: Restore reserved headroom after xmit program","descriptions":[{"lang":"en","value":"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->dev->hard_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->dev) in the post-BPF headroom check to match\nthe reservation made before LWT xmit."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"753e5cdcca5474d230d62bb3489e5168ab27c272","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"c488071c3441fa34f5a87cd6c12ce2cc6304f20e","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"a38c0eb447e2dd0120a2ebcdba470f9505ac8907","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"de2b2004e16f2930eb689175e2c1998b0a68d499","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"7d043e24520a273c362be5dd7d9c82796879a49b","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"7cf561843ed0ad57501892a65abb77957e6c800f","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"179a5b2171573d94a25c9aa8e1c9f9ac352ad316","versionType":"git"},{"version":"3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2","status":"affected","lessThan":"5fe7007aed9ad069b2bd77e5d0c875c64f5c0269","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/lwt_bpf.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.10","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/lwt_bpf.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/753e5cdcca5474d230d62bb3489e5168ab27c272"},{"url":"https://git.kernel.org/stable/c/c488071c3441fa34f5a87cd6c12ce2cc6304f20e"},{"url":"https://git.kernel.org/stable/c/a38c0eb447e2dd0120a2ebcdba470f9505ac8907"},{"url":"https://git.kernel.org/stable/c/de2b2004e16f2930eb689175e2c1998b0a68d499"},{"url":"https://git.kernel.org/stable/c/7d043e24520a273c362be5dd7d9c82796879a49b"},{"url":"https://git.kernel.org/stable/c/7cf561843ed0ad57501892a65abb77957e6c800f"},{"url":"https://git.kernel.org/stable/c/179a5b2171573d94a25c9aa8e1c9f9ac352ad316"},{"url":"https://git.kernel.org/stable/c/5fe7007aed9ad069b2bd77e5d0c875c64f5c0269"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:58:58.842Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}