---
id: CVE-2026-43333
title: 'bpf: reject direct access to nullable PTR_TO_BUF pointers'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: reject direct access to nullable PTR_TO_BUF pointers

  check_mem_access() matches PTR_TO_BUF via base_type() which strips
  PTR_MAYBE_NULL, allowing direct dereferenc…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b453361384c2db1c703dacb806d5fd36aec4ceca <
    10bc4a4dcded509c5d5c67d497900c3922c604cd
  - >-
    Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 <
    21a10c06ffae24cb01fd174a7ab7736001d2ea56
  - >-
    Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 <
    8755066f7bd0f4ac46a29d1708c7b20894539252
  - >-
    Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 <
    70abd9d118da2f56beb4ec22e3a29becae373535
  - >-
    Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 <
    63276547debc4d8a73eefb2c5273b2a905c961b0
  - >-
    Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 <
    4f6c99dc0420f1a3d671c1b8ab8a7ac84d9cba09
  - >-
    Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 <
    b0db1accbc7395657c2b79db59fa9fae0d6656f3
  - Linux e982070f8970bb62e69ed7c9cafff886ed200349
  - Linux >= 5.15.37 < 5.15.203
  - Linux >= 5.16.11 < 5.17
  - Linux 5.17
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T15:35:58.323644Z'
published: '2026-05-08'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T15:42:49.460Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43333'
references:
  - url: 'https://git.kernel.org/stable/c/10bc4a4dcded509c5d5c67d497900c3922c604cd'
  - url: 'https://git.kernel.org/stable/c/21a10c06ffae24cb01fd174a7ab7736001d2ea56'
  - url: 'https://git.kernel.org/stable/c/8755066f7bd0f4ac46a29d1708c7b20894539252'
  - url: 'https://git.kernel.org/stable/c/70abd9d118da2f56beb4ec22e3a29becae373535'
  - url: 'https://git.kernel.org/stable/c/63276547debc4d8a73eefb2c5273b2a905c961b0'
  - url: 'https://git.kernel.org/stable/c/4f6c99dc0420f1a3d671c1b8ab8a7ac84d9cba09'
  - url: 'https://git.kernel.org/stable/c/b0db1accbc7395657c2b79db59fa9fae0d6656f3'
tags:
  - cve.org
epss: 0.00123
epssPercentile: 0.02039
ingestedAt: '2026-11-06T15:54:03.935Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

bpf: reject direct access to nullable PTR_TO_BUF pointers

check_mem_access() matches PTR_TO_BUF via base_type() which strips
PTR_MAYBE_NULL, allowing direct dereference without a null check.

Map iterator ctx->key and ctx->value are PTR_TO_BUF | PTR_MAYBE_NULL.
On stop callbacks these are NULL, causing a kernel NULL dereference.

Add a type_may_be_null() guard to the PTR_TO_BUF branch, matching the
existing PTR_TO_BTF_ID pattern.

## Affected

- `Linux >= b453361384c2db1c703dacb806d5fd36aec4ceca < 10bc4a4dcded509c5d5c67d497900c3922c604cd`
- `Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 < 21a10c06ffae24cb01fd174a7ab7736001d2ea56`
- `Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 < 8755066f7bd0f4ac46a29d1708c7b20894539252`
- `Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 < 70abd9d118da2f56beb4ec22e3a29becae373535`
- `Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 < 63276547debc4d8a73eefb2c5273b2a905c961b0`
- `Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 < 4f6c99dc0420f1a3d671c1b8ab8a7ac84d9cba09`
- `Linux >= 20b2aff4bc15bda809f994761d5719827d66c0b4 < b0db1accbc7395657c2b79db59fa9fae0d6656f3`
- `Linux e982070f8970bb62e69ed7c9cafff886ed200349`
- `Linux >= 5.15.37 < 5.15.203`
- `Linux >= 5.16.11 < 5.17`
- `Linux 5.17`

## Remediation

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