---
id: CVE-2026-98033
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Preserve inner map identity in callback frames

  Callback frame constructors initialize map-typed argument registers with
  __mark_reg_known_zero() and then restore m…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Preserve inner map identity in callback frames

  Callback frame constructors initialize map-typed argument registers with
  __mark_reg_known_zero() and then restore m…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 69c087ba6225b574afb6e505b72cb75242a3d844 <
    66ff2eff093d2a0838f39c713eeb590bc0946c2a
  - >-
    Linux >= 69c087ba6225b574afb6e505b72cb75242a3d844 <
    b90c5d770dad910fb89e6c1b15052a8a1e8db752
  - Linux 5.13
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:32.003'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98033'
references:
  - url: 'https://git.kernel.org/stable/c/66ff2eff093d2a0838f39c713eeb590bc0946c2a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b90c5d770dad910fb89e6c1b15052a8a1e8db752'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.851Z'
---

## Overview

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

bpf: Preserve inner map identity in callback frames

Callback frame constructors initialize map-typed argument registers with
__mark_reg_known_zero() and then restore map_ptr. This clears map_uid,
which is the only field distinguishing inner maps that share an
inner_map_meta template.

When a timer callback invokes bpf_for_each_map_elem() on a second inner
map, both the saved first map and the second map value can reach the nested
callback as the same template with map_uid zero. bpf_timer_init() then
accepts pairing the timer from the second map with the first map.

The runtime records the first map in the timer without taking a reference.
Freeing that map does not find the timer stored in the second map, so a
later timer callback dereferences the freed map.

Copy map_uid from the same caller register as map_ptr when constructing
for-each, timer/workqueue, and task-work callback arguments. The existing
identity check can then reject mismatched inner maps while allowing a
callback value to be paired with its actual map.

## Remediation

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