---
id: CVE-2026-98631
title: 'xsk: Use a 32-bit compare in xsk_map_gen_lookup'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  xsk: Use a 32-bit compare in xsk_map_gen_lookup

  xsk_map_gen_lookup() loads a u32 key and compares it with max_entries
  using BPF_JMP_IMM. BPF immediates are sign-extend…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    c6d5c582d55a8f229d75e98d62eaa065b0deb18d
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    227ec890559e922e235eb543646e3bf0bd8269b0
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    11d9be35c1f4233798e99be98bc474f83a254c6c
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    123f90f394ca404ab8796a7c8072ff7fa5b65a9c
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    36461e58f88a1b723f86693f437ac12e60ff4363
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    b5c0cff0c5331582ab01c4c423731453a8381acc
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24
  - >-
    Linux >= e65650f291ee72fc578d6346080fc4699204ef2c <
    70504de0bb627848667207bec7ccfd647deb8814
  - Linux 5.5
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:19:53.529Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98631'
references:
  - url: 'https://git.kernel.org/stable/c/c6d5c582d55a8f229d75e98d62eaa065b0deb18d'
  - url: 'https://git.kernel.org/stable/c/227ec890559e922e235eb543646e3bf0bd8269b0'
  - url: 'https://git.kernel.org/stable/c/11d9be35c1f4233798e99be98bc474f83a254c6c'
  - url: 'https://git.kernel.org/stable/c/123f90f394ca404ab8796a7c8072ff7fa5b65a9c'
  - url: 'https://git.kernel.org/stable/c/36461e58f88a1b723f86693f437ac12e60ff4363'
  - url: 'https://git.kernel.org/stable/c/b5c0cff0c5331582ab01c4c423731453a8381acc'
  - url: 'https://git.kernel.org/stable/c/3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24'
  - url: 'https://git.kernel.org/stable/c/70504de0bb627848667207bec7ccfd647deb8814'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.234Z'
---

## Overview

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

xsk: Use a 32-bit compare in xsk_map_gen_lookup

xsk_map_gen_lookup() loads a u32 key and compares it with max_entries
using BPF_JMP_IMM. BPF immediates are sign-extended to 64 bits, so a
max_entries value of 0x80000000 or higher becomes a threshold larger
than every zero-extended 32-bit key. An out-of-range index then skips
the bounds check and the generated lookup reads past xsk_map[].

Compare with BPF_JMP32_IMM so the check stays in 32-bit unsigned range.

## Affected

- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < c6d5c582d55a8f229d75e98d62eaa065b0deb18d`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < 227ec890559e922e235eb543646e3bf0bd8269b0`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < 11d9be35c1f4233798e99be98bc474f83a254c6c`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < 123f90f394ca404ab8796a7c8072ff7fa5b65a9c`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < 36461e58f88a1b723f86693f437ac12e60ff4363`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < b5c0cff0c5331582ab01c4c423731453a8381acc`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < 3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24`
- `Linux >= e65650f291ee72fc578d6346080fc4699204ef2c < 70504de0bb627848667207bec7ccfd647deb8814`
- `Linux 5.5`

## Remediation

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