{"id":"CVE-2026-98042","summary":"bpf: Don't resurrect a scalar id dropped by collect_linked_regs()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Don't resurrect a scalar id dropped by collect_linked_regs()\n\ncheck_cond_jmp_op() copies the compared registers into\nenv-\u003e{false,true}_reg{1,2} before collect_linked_regs() runs and copies\nthose snapshots back into both branch states afterwards.\n\ncollect_linked_regs() records at most LINKED_REGS_MAX members of a\nlinked registers group in the jump history and calls clear_scalar_id()\nfor every member that does not fit. The compared register is not exempt\nfrom that.\n\nAs a consequence, sync_linked_regs() might adjust ranges for more\nregisters than bpf_bt_sync_linked_regs() can propagate precision to.\n\nCollect the linked registers before the snapshots are taken instead.\nThis might lead to some unnecessary clear_scalar_id's, but from\nprevious testing situations with many linked registers are\nextremely rare.","modified":"2026-09-26T03:48:37.131311503Z","published":"2026-09-25T10:23:54.242Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98042.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/73a98f96811e2cb0f4210b1caa8cb322f92f2a2b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e821ff19b8ef08255ff8d8234774ed814637e9bf"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98042.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98042"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ec1d77cb0ee98249142dcd0376d76e7a48ba0b31"},{"fixed":"e821ff19b8ef08255ff8d8234774ed814637e9bf"},{"fixed":"73a98f96811e2cb0f4210b1caa8cb322f92f2a2b"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98042.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.1.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98042.json"}}],"schema_version":"1.9.0"}