---
id: CVE-2025-68262
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  crypto: zstd - fix double-free in per-CPU stream cleanup

  The crypto/zstd module has a double-free bug that occurs when multiple
  tfms are allocated and freed.

  The issu…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  crypto: zstd - fix double-free in per-CPU stream cleanup

  The crypto/zstd module has a double-free bug that occurs when multiple
  tfms are allocated and freed.

  The issu…
severity: none
published: '2025-12-16'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68262'
references:
  - url: 'https://git.kernel.org/stable/c/48bc9da3c97c15f1ea24934bcb3b736acd30163d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dc0f4509b0ed5d82bef78e058db0ac4df04d0695'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e983feaa79de1e46c9087fb9f02fedb0e5397ce6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00184
epssPercentile: 0.0738
ingestedAt: '2026-10-14T13:30:58.474Z'
---

## Overview

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

crypto: zstd - fix double-free in per-CPU stream cleanup

The crypto/zstd module has a double-free bug that occurs when multiple
tfms are allocated and freed.

The issue happens because zstd_streams (per-CPU contexts) are freed in
zstd_exit() during every tfm destruction, rather than being managed at
the module level.  When multiple tfms exist, each tfm exit attempts to
free the same shared per-CPU streams, resulting in a double-free.

This leads to a stack trace similar to:

  BUG: Bad page state in process kworker/u16:1  pfn:106fd93
  page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x106fd93
  flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff)
  page_type: 0xffffffff()
  raw: 0017ffffc0000000 dead000000000100 dead000000000122 0000000000000000
  raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
  page dumped because: nonzero entire_mapcount
  Modules linked in: ...
  CPU: 3 UID: 0 PID: 2506 Comm: kworker/u16:1 Kdump: loaded Tainted: G    B
  Hardware name: ...
  Workqueue: btrfs-delalloc btrfs_work_helper
  Call Trace:
   <TASK>
   dump_stack_lvl+0x5d/0x80
   bad_page+0x71/0xd0
   free_unref_page_prepare+0x24e/0x490
   free_unref_page+0x60/0x170
   crypto_acomp_free_streams+0x5d/0xc0
   crypto_acomp_exit_tfm+0x23/0x50
   crypto_destroy_tfm+0x60/0xc0
   ...

Change the lifecycle management of zstd_streams to free the streams only
once during module cleanup.

## Remediation

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