{"schema":"threatline.record/2","record":{"id":"CVE-2026-98040","aliases":[],"summary":"bpf: Mark the zero register precise for a register-form NULL check","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Mark the zero register precise for a register-form NULL check\n\ncheck_cond_jmp_op() accepts \"if rA <op> rB\" as a NULL check for a\nnullable pointer rA when rB is a scalar known to be zero,\nlifts PTR_MAYBE_NULL from rA in the corresponding branch and does not\nmark rB precise. Consider the following program:\n\n  r0 = bpf_get_prandom_u32();\n  r6 = 1;                  /* the r6 == 0 path is explored first */\n  if (r0 == 0) goto 1f;\n  r6 = 0;\n1:\n  r0 = bpf_map_lookup_elem(map, &0);  /* absent, NULL at runtime */\n  if (r0 == r6) goto 2f;   /* taken as a NULL check for r0       */\n  *(u8 *)(r0 + 0);         /* verifier: map value; runtime: zero */\n2:\n  return 0;\n\nThe r6 == 0 path is explored first and the dereference is accepted.\nThe r6 == 1 path is pruned at the checkpoint recorded for (1),\nso the comparison is never verified with a non-zero r6. At runtime a\nfailed lookup returns NULL, NULL != 1 takes the non-NULL edge and the\nprogram dereferences a pointer that is zero.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98040","source_modified_at":"2026-10-19T09:12:46.084Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"2f4cb53eed448c1aeb6f4b40cf9c810716d8218c","lessThan":"ddca9a3b8833168dda3e62676648a636fb3f221c","status":"affected","versionType":"git"},{"version":"2f4cb53eed448c1aeb6f4b40cf9c810716d8218c","lessThan":"6aed0134d3cda6382385a734ae0158eb7df6b142","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98040","source_modified_at":"2026-10-19T09:12:46.084Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"7.1","status":"affected"},{"version":"0","lessThan":"7.1","status":"unaffected","versionType":"semver"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98040","source_modified_at":"2026-10-19T09:12:46.084Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"6aed0134d3cda6382385a734ae0158eb7df6b142","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00189,"percentile":0.08121,"score_date":"2026-10-23"},"published_at":"2026-09-25T10:23:53.001Z","modified_at":"2026-10-19T09:12:46.084Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98040","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:12:46.084Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98040","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/ddca9a3b8833168dda3e62676648a636fb3f221c"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/6aed0134d3cda6382385a734ae0158eb7df6b142"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:12:46.084Z","content_hash":"58a1a95b5369d68274be26ba2f3610b63a838c2d637834871ba6b910d61d37c2"}}