bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()
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: bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321)
CVE-2026-45839
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-45839
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "c8e49b79c4b48bd687706ff6e9c82638dc81ef80",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "a9e777f856cd2f1efc106afc7bf21aef868509d5",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "669349b4612c26b3d7aacfa99d7174681bd19223",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "3ff85ae79e1a74baeb916b78a63d821f6d19a994",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "76f2ebaf79a9ae6d0737b87f045fe769e425d78f",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2",
"versionType": "git"
},
{
"status": "affected",
"version": "ddc7c3042614e273044f698d2beab25cc3842d45",
"lessThan": "1c22483a2c4bbf747787f328392ca3e68619c4dc",
"versionType": "git"
}
],
"programFiles": [
"tools/lib/bpf/relo_core.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.4"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.4",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.267",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.209",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.175",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.141",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.91",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.33",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.10",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"tools/lib/bpf/relo_core.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-45839
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #28363 · Revision 1
- Added to Heist Feed
- Publisher date