---
id: CVE-2026-45839
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()

  CO-RE accessor strings are colon-separated indices that describe a path
  from a root BTF type to a …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()

  CO-RE accessor strings are colon-separated indices that describe a path
  from 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: 0.00176
epssPercentile: 0.06382
ingestedAt: '2026-08-27T17:05:19.728Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()

CO-RE accessor strings are colon-separated indices that describe a path
from a root BTF type to a target field, e.g. "0:1:2" walks through
nested struct members. bpf_core_parse_spec() parses each component with
sscanf("%d"), so negative values like -1 are silently accepted.  The
subsequent bounds checks (access_idx >= btf_vlen(t)) only guard the
upper bound and always pass for negative values because C integer
promotion converts the __u16 btf_vlen result to int, making the
comparison (int)(-1) >= (int)(N) false for any positive N.

When -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff,
producing an out-of-bounds read far past the members array.  A crafted
BPF program with a negative CO-RE accessor on any struct that exists in
vmlinux BTF (e.g. task_struct) crashes the kernel deterministically
during BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y
(default on major distributions).  The bug is reachable with CAP_BPF:

 BUG: unable to handle page fault for address: ffffed11818b6626
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 Oops: Oops: 0000 [#1] SMP KASAN NOPTI
 CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full)
 RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354)
 RAX: 00000000ffffffff
 Call Trace:
  <TASK>
  bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321)
  bpf_core_apply (kernel/bpf/btf.c:9507)
  check_core_relo (kernel/bpf/verifier.c:19475)
  bpf_check (kernel/bpf/verifier.c:26031)
  bpf_prog_load (kernel/bpf/syscall.c:3089)
  __sys_bpf (kernel/bpf/syscall.c:6228)
  </TASK>

CO-RE accessor indices are inherently non-negative (struct member index,
array element index, or enumerator index), so reject them immediately
after parsing.

## 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`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.10`