{"id":"CVE-2026-45839","state":"PUBLISHED","title":"bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()\n\nCO-RE accessor strings are colon-separated indices that describe a path\nfrom a root BTF type to a target field, e.g. \"0:1:2\" walks through\nnested struct members. bpf_core_parse_spec() parses each component with\nsscanf(\"%d\"), so negative values like -1 are silently accepted.  The\nsubsequent bounds checks (access_idx >= btf_vlen(t)) only guard the\nupper bound and always pass for negative values because C integer\npromotion converts the __u16 btf_vlen result to int, making the\ncomparison (int)(-1) >= (int)(N) false for any positive N.\n\nWhen -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff,\nproducing an out-of-bounds read far past the members array.  A crafted\nBPF program with a negative CO-RE accessor on any struct that exists in\nvmlinux BTF (e.g. task_struct) crashes the kernel deterministically\nduring BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y\n(default on major distributions).  The bug is reachable with CAP_BPF:\n\n BUG: unable to handle page fault for address: ffffed11818b6626\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n Oops: Oops: 0000 [#1] SMP KASAN NOPTI\n CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full)\n RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354)\n RAX: 00000000ffffffff\n Call Trace:\n  <TASK>\n  bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321)\n  bpf_core_apply (kernel/bpf/btf.c:9507)\n  check_core_relo (kernel/bpf/verifier.c:19475)\n  bpf_check (kernel/bpf/verifier.c:26031)\n  bpf_prog_load (kernel/bpf/syscall.c:3089)\n  __sys_bpf (kernel/bpf/syscall.c:6228)\n  </TASK>\n\nCO-RE accessor indices are inherently non-negative (struct member index,\narray element index, or enumerator index), so reject them immediately\nafter parsing.","publishedAt":"2026-05-27T09:24:37.855Z","updatedAt":"2026-10-15T01:19:41.412Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"c8e49b79c4b48bd687706ff6e9c82638dc81ef80","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"a9e777f856cd2f1efc106afc7bf21aef868509d5","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"669349b4612c26b3d7aacfa99d7174681bd19223","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"3ff85ae79e1a74baeb916b78a63d821f6d19a994","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"76f2ebaf79a9ae6d0737b87f045fe769e425d78f","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"1c22483a2c4bbf747787f328392ca3e68619c4dc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["tools/lib/bpf/relo_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"5.10.267","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.141","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.91","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["tools/lib/bpf/relo_core.c"]}],"references":["https://git.kernel.org/stable/c/c8e49b79c4b48bd687706ff6e9c82638dc81ef80","https://git.kernel.org/stable/c/a9e777f856cd2f1efc106afc7bf21aef868509d5","https://git.kernel.org/stable/c/669349b4612c26b3d7aacfa99d7174681bd19223","https://git.kernel.org/stable/c/3ff85ae79e1a74baeb916b78a63d821f6d19a994","https://git.kernel.org/stable/c/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a","https://git.kernel.org/stable/c/76f2ebaf79a9ae6d0737b87f045fe769e425d78f","https://git.kernel.org/stable/c/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2","https://git.kernel.org/stable/c/1c22483a2c4bbf747787f328392ca3e68619c4dc","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/45xxx/CVE-2026-45839.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-45839","state":"PUBLISHED","datePublished":"2026-05-27T09:24:37.855Z","dateUpdated":"2026-10-15T01:19:41.412Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.077Z"},"containers":{"cna":{"title":"bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()\n\nCO-RE accessor strings are colon-separated indices that describe a path\nfrom a root BTF type to a target field, e.g. \"0:1:2\" walks through\nnested struct members. bpf_core_parse_spec() parses each component with\nsscanf(\"%d\"), so negative values like -1 are silently accepted.  The\nsubsequent bounds checks (access_idx >= btf_vlen(t)) only guard the\nupper bound and always pass for negative values because C integer\npromotion converts the __u16 btf_vlen result to int, making the\ncomparison (int)(-1) >= (int)(N) false for any positive N.\n\nWhen -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff,\nproducing an out-of-bounds read far past the members array.  A crafted\nBPF program with a negative CO-RE accessor on any struct that exists in\nvmlinux BTF (e.g. task_struct) crashes the kernel deterministically\nduring BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y\n(default on major distributions).  The bug is reachable with CAP_BPF:\n\n BUG: unable to handle page fault for address: ffffed11818b6626\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n Oops: Oops: 0000 [#1] SMP KASAN NOPTI\n CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full)\n RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354)\n RAX: 00000000ffffffff\n Call Trace:\n  <TASK>\n  bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321)\n  bpf_core_apply (kernel/bpf/btf.c:9507)\n  check_core_relo (kernel/bpf/verifier.c:19475)\n  bpf_check (kernel/bpf/verifier.c:26031)\n  bpf_prog_load (kernel/bpf/syscall.c:3089)\n  __sys_bpf (kernel/bpf/syscall.c:6228)\n  </TASK>\n\nCO-RE accessor indices are inherently non-negative (struct member index,\narray element index, or enumerator index), so reject them immediately\nafter parsing."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"c8e49b79c4b48bd687706ff6e9c82638dc81ef80","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"a9e777f856cd2f1efc106afc7bf21aef868509d5","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"669349b4612c26b3d7aacfa99d7174681bd19223","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"3ff85ae79e1a74baeb916b78a63d821f6d19a994","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"76f2ebaf79a9ae6d0737b87f045fe769e425d78f","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2","versionType":"git"},{"version":"ddc7c3042614e273044f698d2beab25cc3842d45","status":"affected","lessThan":"1c22483a2c4bbf747787f328392ca3e68619c4dc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["tools/lib/bpf/relo_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"5.10.267","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.141","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.91","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["tools/lib/bpf/relo_core.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c8e49b79c4b48bd687706ff6e9c82638dc81ef80"},{"url":"https://git.kernel.org/stable/c/a9e777f856cd2f1efc106afc7bf21aef868509d5"},{"url":"https://git.kernel.org/stable/c/669349b4612c26b3d7aacfa99d7174681bd19223"},{"url":"https://git.kernel.org/stable/c/3ff85ae79e1a74baeb916b78a63d821f6d19a994"},{"url":"https://git.kernel.org/stable/c/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a"},{"url":"https://git.kernel.org/stable/c/76f2ebaf79a9ae6d0737b87f045fe769e425d78f"},{"url":"https://git.kernel.org/stable/c/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2"},{"url":"https://git.kernel.org/stable/c/1c22483a2c4bbf747787f328392ca3e68619c4dc"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-27T12:39:38.923Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.10.267"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.6.141"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.12.91"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.18.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"7.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC 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