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CVE-2026-45839— bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于bpf_core_parse_spec使用sscanf解析CO-RE访问器索引时接受负值且边界检查仅保护上限，可能导致负值到达btf_member_bit_offset时转换为u32 0xffffffff产生越界读取导致内核崩溃。

AI Predicted 7.8 Difficulty: Hard EPSS 0.13% · P3

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux ddc7c3042614e273044f698d2beab25cc3842d45< c8e49b79c4b48bd687706ff6e9c82638dc81ef80 affected
ddc7c3042614e273044f698d2beab25cc3842d45< a9e777f856cd2f1efc106afc7bf21aef868509d5 affected
ddc7c3042614e273044f698d2beab25cc3842d45< 669349b4612c26b3d7aacfa99d7174681bd19223 affected
ddc7c3042614e273044f698d2beab25cc3842d45< 3ff85ae79e1a74baeb916b78a63d821f6d19a994 affected
ddc7c3042614e273044f698d2beab25cc3842d45< 36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a affected
ddc7c3042614e273044f698d2beab25cc3842d45< 76f2ebaf79a9ae6d0737b87f045fe769e425d78f affected
ddc7c3042614e273044f698d2beab25cc3842d45< 99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2 affected
ddc7c3042614e273044f698d2beab25cc3842d45< 1c22483a2c4bbf747787f328392ca3e68619c4dc affected
… +10 more rows
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I. Basic Information for CVE-2026-45839

Vulnerability Information
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Vulnerability Title
bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于bpf_core_parse_spec使用sscanf解析CO-RE访问器索引时接受负值且边界检查仅保护上限，可能导致负值到达btf_member_bit_offset时转换为u32 0xffffffff产生越界读取导致内核崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux ddc7c3042614e273044f698d2beab25cc3842d45 ~ c8e49b79c4b48bd687706ff6e9c82638dc81ef80 -
Linux Linux 5.4 -

II. Public POCs for CVE-2026-45839

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III. Intelligence Information for CVE-2026-45839

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Patches & Fixes for CVE-2026-45839 (6)

Other References for CVE-2026-45839 (1)

Same Patch Batch · Linux · 2026-05-27 · 275 CVEs total

CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
CVE-2026-46037 8.2 HIGH ipv4: icmp: validate reply type before using icmp_pointers
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2026-46099 8.1 HIGH net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
CVE-2026-46010 8.1 HIGH rxrpc: Fix error handling in rxgk_extract_token()
CVE-2026-46076 7.9 HIGH KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1
CVE-2026-45910 7.8 HIGH RDMA/rxe: Fix race condition in QP timer handlers
CVE-2026-45931 7.8 HIGH accel/amdxdna: Hold mm structure across iommu_sva_unbind_device()
CVE-2026-45956 7.8 HIGH drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
CVE-2026-46036 7.8 HIGH vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex
CVE-2026-46100 7.8 HIGH fs: afs: revert mmap_prepare() change
CVE-2026-45894 7.8 HIGH iommu/vt-d: Clear Present bit before tearing down PASID entry
CVE-2026-45933 7.8 HIGH bpf: Preserve id of register in sync_linked_regs()

Showing top 20 of 275 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-45839

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