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CVE-2026-74258 (GCVE-0-2026-74258)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:57 – Updated: 2026-08-17 05:45
VLAI
Title
bpf: Guard __get_user acesss with access_ok for uprobe_multi data
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Guard __get_user acesss with access_ok for uprobe_multi data As reported by sashiko [1] we need to use access_ok to check the user space data bounds before we use __get-user to get it. [1] https://lore.kernel.org/bpf/20260610145235.CB1441F00893@smtp.kernel.org/
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 89ae89f53d201143560f1e9ed4bfa62eee34f88e , < c6d51ad36490013ee9df94a372d3bf794bd304d1 (git)
Affected: 89ae89f53d201143560f1e9ed4bfa62eee34f88e , < 4d87a251d45b4a95eb4c0abcfab809c9f231258a (git)
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Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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              "value": "AV:L - The bug is in bpf_uprobe_multi_link_attach(), reached only via the local bpf(BPF_LINK_CREATE) syscall with BPF_TRACE_UPROBE_MULTI; per kernel CNA guidance BPF/uprobe link creation is Local, not network-reachable.\nAC:L - The attacker fully controls link_create.uprobe_multi offsets/ref_ctr_offsets/cookies pointers and cnt, so __get_user runs on attacker-chosen addresses without races or external conditions; repeated attempts reliably leak or fault.\nPR:L - Exploitation requires a BPF_PROG_TYPE_KPROBE program (CAP_BPF+CAP_PERFMON), routinely delegated via BPF tokens into non-init user namespaces for tracing/container workloads; this is low privilege, not init-namespace root.\nUI:N - No victim interaction is needed; the attacker loads the BPF program, issues BPF_LINK_CREATE with crafted pointers, and can read leaked data back via BPF_OBJ_GET_INFO_BY_FD on their own link.\nS:U - Impact is arbitrary kernel memory disclosure and possible host compromise within the same kernel security authority; it does not cross VM, IOMMU, or container sandbox boundaries by itself.\nC:H - Missing access_ok lets __get_user copy from kernel addresses into uprobes arrays (up to cnt*8 bytes); cookies/offsets can be exfiltrated through bpf_uprobe_multi_link_fill_link_info, giving arbitrary kernel memory read.\nI:H - Leaked kernel pointers and attacker-influenced offset/ref_ctr values feed uprobe_register() breakpoint installation, and the read primitive is standardly chained into arbitrary kernel write and privilege escalation.\nA:H - __get_user on non-userspace addresses can fault under SMAP/PAN and oops the kernel; even failed exploitation attempts can crash the host, and guidance treats serious uaccess bugs as high availability impact."
            }
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    "dateReserved": "2026-08-15T05:44:03.877Z",
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      "title": "bpf: Guard __get_user acesss with access_ok for uprobe_multi data",
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    "redhat_vex": {
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      "cve": "CVE-2026-74258",
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      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "184",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Guard __get_user acesss with access_ok for uprobe_multi data",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74258.json",
      "version": "3"
    }
  }
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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