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CVE-2025-39990 (GCVE-0-2025-39990)

Vulnerability from cvelistv5 – Published: 2025-10-15 07:56 – Updated: 2026-08-05 12:06
VLAI
Title
bpf: Check the helper function is valid in get_helper_proto
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Check the helper function is valid in get_helper_proto kernel test robot reported verifier bug [1] where the helper func pointer could be NULL due to disabled config option. As Alexei suggested we could check on that in get_helper_proto directly. Marking tail_call helper func with BPF_PTR_POISON, because it is unused by design. [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com
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: f470378c7562a2818b45ed11c98973f2b89eedd3 , < 3d429cb1278e995e22995ef117fa96d223a67e93 (git)
Affected: f470378c7562a2818b45ed11c98973f2b89eedd3 , < 6233715b4b714068d6c831d214a4e8792109875a (git)
Affected: f470378c7562a2818b45ed11c98973f2b89eedd3 , < e4414b01c1cd9887bbde92f946c1ba94e40d6d64 (git)
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Linux Linux Affected: 5.8
Unaffected: 0 , < 5.8 (semver)
Unaffected: 6.12.50 , ≤ 6.12.* (semver)
Unaffected: 6.16.10 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/core.c",
            "kernel/bpf/verifier.c"
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          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "versionType": "semver"
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              "operator": "OR"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Check the helper function is valid in get_helper_proto\n\nkernel test robot reported verifier bug [1] where the helper func\npointer could be NULL due to disabled config option.\n\nAs Alexei suggested we could check on that in get_helper_proto\ndirectly. Marking tail_call helper func with BPF_PTR_POISON,\nbecause it is unused by design.\n\n  [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com"
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            "baseSeverity": "HIGH",
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            "version": "3.1"
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              "value": "AV:L - The vulnerability is reached only through the local `bpf(BPF_PROG_LOAD)` syscall, which is used to submit the crafted program to the verifier. There is no remote or adjacent-network path into `get_helper_proto()`.\nAC:L - On an affected build the attacker deterministically triggers the bug every time by loading a program that calls a helper whose weak proto is zeroed \u2014 no race, no memory-layout dependency, no unpredictable state. Both the `verifier_bug()` WARN path and the `bpf_get_branch_snapshot` inline path are fully under the attacker\u0027s control via the program bytecode.\nPR:L - Program load plus `CAP_PERFMON`/`CAP_BPF` is required, but `CAP_PERFMON` is a narrow, non-root capability commonly granted to unprivileged profiling and BPF observability daemons, and `bpf_token_capable()` explicitly makes it delegable to unprivileged users inside user namespaces via bpffs BPF tokens. This is an ordinary low-privileged account boundary, not init-namespace root.\nUI:N - The attacker loads and exercises the BPF program entirely on their own; no other user or administrator has to perform any action.\nS:U - The corruption and the crash both occur inside the kernel that is already the security authority for the calling process \u2014 a conventional local kernel privilege-escalation/DoS, with no VM, IOMMU, or sandbox boundary crossed.\nC:H - With all `arg_type[]` zeroed to `ARG_DONTCARE` the verifier validates nothing, and the inlined `bpf_get_branch_snapshot` copies LBR records (kernel from/to instruction pointers) to an attacker-chosen destination that can be a readable BPF map value, disclosing kernel text addresses and defeating KASLR; the same unvalidated-pointer primitive generalizes to broader kernel memory disclosure.\nI:H - `__intel_pmu_snapshot_branch_stack()` performs `memcpy(entries, cpuc-\u003elbr_entries, 24 * cnt)` with `entries` an entirely unvalidated attacker-supplied scalar, giving an arbitrary kernel-memory write of up to several hundred bytes \u2014 a direct privilege-escalation primitive.\nA:H - The common path hits `verifier_bug()` \u2192 `BPF_WARN_ONCE`, which taints the kernel and panics outright on the many hardened/production and Android kernels that set `panic_on_warn=1`; the arbitrary-write path trivially oopses the kernel by targeting unmapped or critical memory."
            }
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        "dateUpdated": "2026-08-05T12:06:56.969Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/3d429cb1278e995e22995ef117fa96d223a67e93"
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          "url": "https://git.kernel.org/stable/c/e4414b01c1cd9887bbde92f946c1ba94e40d6d64"
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    "assignerShortName": "Linux",
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    "datePublished": "2025-10-15T07:56:07.295Z",
    "dateReserved": "2025-04-16T07:20:57.150Z",
    "dateUpdated": "2026-08-05T12:06:56.969Z",
    "state": "PUBLISHED"
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      "product_status:known_affected": "18",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "bpf: Check the helper function is valid in get_helper_proto",
      "url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-39990.json",
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    "redhat_vex": {
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      "cve": "CVE-2025-39990",
      "id": "CVE-2025-39990",
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      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-39990",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-39990.json",
      "version": "24"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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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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