# CVE-2025-68262: linux: In the Linux kernel, the following vulnerability has been resolved:  crypto: zstd - fix double-free in per-CPU stream...

CVE-2025-68262 is fixed in linux on 1 platform by DEBIAN-CVE-2025-68262 (version 6.17.12-1), released December 16, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-68262
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 16, 2025

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.17.12-1 | [DEBIAN-CVE-2025-68262](https://patchblox.com/security/data/fix/linux/debian-cve-2025-68262.md) | Dec 16, 2025 |

---

Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.