Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9 relo_core.c bpf_core_parse_spec out-of-bounds

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9. It has been rated as critical. This issue affects the function bpf_core_parse_spec in the library tools/lib/bpf/relo_core.c. Performing a manipulation results in out-of-bounds. This vulnerability is identified as CVE-2026-45839. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9. This affects the function bpf_core_parse_spec in the library tools/lib/bpf/relo_core.c. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-45839 since 05/13/2026. The exploitability is told to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 321868 (Debian dsa-6355 : ata-modules-6.12.90+deb13-armmp-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.141, 6.12.91, 6.18.33, 7.0.10 or 7.1-rc1 eliminates this vulnerability. Applying the patch 3ff85ae79e1a74baeb916b78a63d821f6d19a994/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a/76f2ebaf79a9ae6d0737b87f045fe769e425d78f/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2/1c22483a2c4bbf747787f328392ca3e68619c4dc is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (321868) and CERT Bund (WID-SEC-2026-1691). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • SUSE Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • Ubuntu Linux

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 2.6
VulDB Temp Score: 2.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 321868
Nessus Name: Debian dsa-6355 : ata-modules-6.12.90+deb13-armmp-di - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.141/6.12.91/6.18.33/7.0.10/7.1-rc1
Patch: 3ff85ae79e1a74baeb916b78a63d821f6d19a994/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a/76f2ebaf79a9ae6d0737b87f045fe769e425d78f/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2/1c22483a2c4bbf747787f328392ca3e68619c4dc

Timelineinfo

05/13/2026 CVE reserved
05/27/2026 +14 days Advisory disclosed
05/27/2026 +0 days VulDB entry created
07/22/2026 +56 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-45839 (🔒)
GCVE (CVE): GCVE-0-2026-45839
GCVE (VulDB): GCVE-100-366051
CERT Bund: WID-SEC-2026-1691 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/27/2026 13:46
Updated: 07/22/2026 13:32
Changes: 05/27/2026 13:46 (59), 05/27/2026 15:53 (7), 06/15/2026 12:29 (1), 06/21/2026 21:51 (2), 06/26/2026 23:07 (12), 07/22/2026 13:32 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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