---
id: CVE-2026-98044
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Reject legacy packet loads from callbacks

  check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a
  subprogram as an implicit return with R0 set to zero
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  bpf: Reject legacy packet loads from callbacks

  check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a
  subprogram as an implicit return with R0 set to zero. It ca…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= ce01a4e5cfac7adbe0be565f90cd32ecbb2f8337 <
    3484a99303912db62428494a9061212049027e57
  - >-
    Linux >= ee861486e377edc55361c08dcbceab3f6b6577bd <
    bc489c0c9b8c86bd7fac42cfd1bb152f042fca56
  - >-
    Linux >= ee861486e377edc55361c08dcbceab3f6b6577bd <
    e7d28823c662128caae63f14e16bd394916c139b
  - Linux 928d354ae3557e8f755a227e67be88034eb3cd7f
  - Linux 8a800497d9f6c2ec9c2c1ba7b71d0ac2ea7f7bbe
  - Linux de1055e7f9e67af32b1f3376066272b04e5223c0
  - Linux 37ad2bb11e9de92cb7b94548705eeedd87f7d392
  - Linux 8674e2db06cff6b50f2216eed9a761d15425bb34
  - Linux d846d83bdacbd8f14fc45c63b8c1d22608452e1c
  - Linux >= 6.18.42 < 6.18.53
  - Linux >= 5.10.265 < 5.11
  - Linux >= 5.15.216 < 5.16
  - Linux >= 6.1.183 < 6.2
  - Linux >= 6.6.148 < 6.7
  - Linux >= 6.12.101 < 6.13
  - Linux >= 7.0.10 < 7.1
  - Linux 7.1
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:33.200'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98044'
references:
  - url: 'https://git.kernel.org/stable/c/3484a99303912db62428494a9061212049027e57'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bc489c0c9b8c86bd7fac42cfd1bb152f042fca56'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e7d28823c662128caae63f14e16bd394916c139b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.848Z'
---

## Overview

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

bpf: Reject legacy packet loads from callbacks

check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a
subprogram as an implicit return with R0 set to zero. It calls
prepare_func_exit() to explore this synthesized path.

When the load is reached directly from a synchronous callback,
prepare_func_exit() enforces the callback return contract and marks R0
precise. R0 is not derived from a real instruction on this path, so
precision backtracking reaches the callback call with R0 still requested
and triggers the "callback unexpected regs" verifier bug. A privileged
program loader can therefore cause a verifier warning and an -EFAULT
BPF_PROG_LOAD.

These legacy packet-load instructions are deprecated. Reject them from
callbacks rather than complicating their implicit-return model. Check all
active frames before constructing the implicit return so nested static
subprograms cannot hide the callback context.

Global functions are verified independently with a fresh frame zero, so
an active-frame check cannot identify a global function called from a
callback. Also check the complete subprogram call graph during stack-depth
validation and reject a function containing a legacy load when any caller
is a callback. This covers global and static descendants without making
has_ld_abs transitive, preserving its per-function BTF return-type check.
Ordinary uses outside callbacks remain supported.

## Remediation

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