Linux Kernel up to 6.16-rc5 nbd nbd_genl_connect use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.7$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.16-rc5. It has been declared as critical. Affected by this vulnerability is the function nbd_genl_connect of the component nbd. Executing a manipulation can lead to use after free. This vulnerability is registered as CVE-2025-38443. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.16-rc5. It has been declared as critical. This vulnerability affects the function nbd_genl_connect of the component nbd. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: nbd: fix uaf in nbd_genl_connect() error path There is a use-after-free issue in nbd: block nbd6: Receive control failed (result -104) block nbd6: shutting down sockets ================================================================== BUG: KASAN: slab-use-after-free in recv_work+0x694/0xa80 drivers/block/nbd.c:1022 Write of size 4 at addr ffff8880295de478 by task kworker/u33:0/67 CPU: 2 UID: 0 PID: 67 Comm: kworker/u33:0 Not tainted 6.15.0-rc5-syzkaller-00123-g2c89c1b655c0 #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: nbd6-recv recv_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline] recv_work+0x694/0xa80 drivers/block/nbd.c:1022 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> nbd_genl_connect() does not properly stop the device on certain error paths after nbd_start_device() has been called. This causes the error path to put nbd->config while recv_work continue to use the config after putting it, leading to use-after-free in recv_work. This patch moves nbd_start_device() after the backend file creation.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2025-38443 since 04/16/2025. The exploitation appears to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 01/03/2026).

The vulnerability scanner Nessus provides a plugin with the ID 265984 (Ubuntu Pro FIPS-updates 22.04 LTS : Linux kernel (Azure FIPS) vulnerabilities (USN-7775-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.189, 6.1.146, 6.6.99, 6.12.39, 6.15.7 or 6.16-rc6 eliminates this vulnerability. Applying the patch cb121c47f364b51776c4db904a6a5a90ab0a7ec5/91fa560c73a8126868848ed6cd70607cbf8d87e2/d46186eb7bbd9a11c145120f2d77effa8d4d44c2/8586552df591e0a367eff44af0c586213eeecc3f/002aca89753f666d878ca0eb8584c372684ac4ba/aa9552438ebf015fc5f9f890dbfe39f0c53cf37e is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (265984), EUVD (EUVD-2025-22698) and CERT Bund (WID-SEC-2025-1653). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • Dell NetWorker
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 265984
Nessus Name: Ubuntu Pro FIPS-updates 22.04 LTS : Linux kernel (Azure FIPS) vulnerabilities (USN-7775-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.189/6.1.146/6.6.99/6.12.39/6.15.7/6.16-rc6
Patch: cb121c47f364b51776c4db904a6a5a90ab0a7ec5/91fa560c73a8126868848ed6cd70607cbf8d87e2/d46186eb7bbd9a11c145120f2d77effa8d4d44c2/8586552df591e0a367eff44af0c586213eeecc3f/002aca89753f666d878ca0eb8584c372684ac4ba/aa9552438ebf015fc5f9f890dbfe39f0c53cf37e

Timelineinfo

04/16/2025 CVE reserved
07/25/2025 +100 days Advisory disclosed
07/25/2025 +0 days VulDB entry created
01/03/2026 +162 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38443 (🔒)
GCVE (CVE): GCVE-0-2025-38443
GCVE (VulDB): GCVE-100-317680
EUVD: 🔒
CERT Bund: WID-SEC-2025-1653 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 07/25/2025 19:03
Updated: 01/03/2026 23:09
Changes: 07/25/2025 19:03 (59), 07/30/2025 02:00 (1), 08/22/2025 11:37 (7), 09/15/2025 02:14 (1), 09/27/2025 03:29 (2), 09/29/2025 00:24 (1), 11/02/2025 13:58 (1), 11/17/2025 06:19 (1), 12/23/2025 00:48 (12), 12/23/2025 08:59 (1), 01/03/2026 23:09 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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