---
id: CVE-2025-39990
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 con…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-476
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 <
    dfbff47f120e4b0793ca0e0b8660361ccac25a74
  - >-
    Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 <
    3d429cb1278e995e22995ef117fa96d223a67e93
  - >-
    Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 <
    6233715b4b714068d6c831d214a4e8792109875a
  - >-
    Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 <
    e4414b01c1cd9887bbde92f946c1ba94e40d6d64
  - Linux 5.8
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:55:55.410522Z'
published: '2025-10-15'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:37:41.130Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39990'
references:
  - url: 'https://git.kernel.org/stable/c/dfbff47f120e4b0793ca0e0b8660361ccac25a74'
  - url: 'https://git.kernel.org/stable/c/3d429cb1278e995e22995ef117fa96d223a67e93'
  - url: 'https://git.kernel.org/stable/c/6233715b4b714068d6c831d214a4e8792109875a'
  - url: 'https://git.kernel.org/stable/c/e4414b01c1cd9887bbde92f946c1ba94e40d6d64'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39990.json
  - url: 'https://access.redhat.com/security/cve/CVE-2025-39990'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2404114'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2025-39990'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-39990'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2025101502-CVE-2025-39990-25bc@gregkh/T
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00198
epssPercentile: 0.09693
scores:
  cna: 7.8
  vendor: 5.5
ingestedAt: '2026-10-15T22:48:25.535Z'
---

## Overview

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

## Affected

- `Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 < dfbff47f120e4b0793ca0e0b8660361ccac25a74`
- `Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 < 3d429cb1278e995e22995ef117fa96d223a67e93`
- `Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 < 6233715b4b714068d6c831d214a4e8792109875a`
- `Linux >= f470378c7562a2818b45ed11c98973f2b89eedd3 < e4414b01c1cd9887bbde92f946c1ba94e40d6d64`
- `Linux 5.8`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39990.json)