{"id":"CVE-2026-45839","title":"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 …","summary":"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 …","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-129"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 5.4, < 5.15.209","linux_kernel >= 5.16, < 6.1.175","linux_kernel >= 6.2, < 6.6.141","linux_kernel >= 6.7, < 6.12.91","linux_kernel >= 6.13, < 6.18.33","linux_kernel >= 6.19, < 7.0.10"],"patched":["linux_kernel 7.0.10"],"published":"2026-05-27","updated":"2026-08-27","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-45839","references":[{"url":"https://git.kernel.org/stable/c/1c22483a2c4bbf747787f328392ca3e68619c4dc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3ff85ae79e1a74baeb916b78a63d821f6d19a994","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/669349b4612c26b3d7aacfa99d7174681bd19223","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/76f2ebaf79a9ae6d0737b87f045fe769e425d78f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a9e777f856cd2f1efc106afc7bf21aef868509d5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c8e49b79c4b48bd687706ff6e9c82638dc81ef80","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00133,"epssPercentile":0.03232,"ingestedAt":"2026-08-27T17:05:19.728Z","slug":"CVE-2026-45839","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel >= 5.4, < 5.15.209`\n- `linux_kernel >= 5.16, < 6.1.175`\n- `linux_kernel >= 6.2, < 6.6.141`\n- `linux_kernel >= 6.7, < 6.12.91`\n- `linux_kernel >= 6.13, < 6.18.33`\n- `linux_kernel >= 6.19, < 7.0.10`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.10`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}