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7.8
HIGH CVSS 3.1
CVE-2025-21731
"Linux NBD Uninitialized Pointer Dereference"
Description

In the Linux kernel, the following vulnerability has been resolved: nbd: don't allow reconnect after disconnect Following process can cause nbd_config UAF: 1) grab nbd_config temporarily; 2) nbd_genl_disconnect() flush all recv_work() and release the initial reference: nbd_genl_disconnect nbd_disconnect_and_put nbd_disconnect flush_workqueue(nbd->recv_workq) if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...)) nbd_config_put -> due to step 1), reference is still not zero 3) nbd_genl_reconfigure() queue recv_work() again; nbd_genl_reconfigure config = nbd_get_config_unlocked(nbd) if (!config) -> succeed if (!test_bit(NBD_RT_BOUND, ...)) -> succeed nbd_reconnect_socket queue_work(nbd->recv_workq, &args->work) 4) step 1) release the reference; 5) Finially, recv_work() will trigger UAF: recv_work nbd_config_put(nbd) -> nbd_config is freed atomic_dec(&config->recv_threads) -> UAF Fix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so that nbd_genl_reconfigure() will fail.

INFO

Published Date :

Feb. 27, 2025, 2:15 a.m.

Last Modified :

March 24, 2025, 6:56 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-21731 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH 134c704f-9b21-4f2e-91b3-4a467353bcc0
Solution
Prevent use-after-free by clearing NBD_RT_BOUND during disconnect.
  • Ensure NBD_RT_BOUND is cleared on disconnect.
  • Prevent reconfigure after disconnect.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-21731.

URL Resource
https://git.kernel.org/stable/c/6bef6222a3f6c7adb6396f77f25a3579d821b09a Patch
https://git.kernel.org/stable/c/844b8cdc681612ff24df62cdefddeab5772fadf1 Patch
https://git.kernel.org/stable/c/9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302 Patch
https://git.kernel.org/stable/c/a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739 Patch
https://git.kernel.org/stable/c/d208d2c52b652913b5eefc8ca434b0d6b757f68f Patch
https://git.kernel.org/stable/c/e3be8862d73cac833e0fb7602636c19c6cb94b11 Patch
https://git.kernel.org/stable/c/e70a578487a47d7cf058904141e586684d1c3381 Patch
https://git.kernel.org/stable/c/e7343fa33751cb07c1c56b666bf37cfca357130e Patch
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-21731 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-21731 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-21731 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-21731 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Mar. 24, 2025

    Action Type Old Value New Value
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.13.2 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.76 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.13 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.179 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 6.1.129 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5 up to (excluding) 5.10.235 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.12 up to (excluding) 5.4.291
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/6bef6222a3f6c7adb6396f77f25a3579d821b09a Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/844b8cdc681612ff24df62cdefddeab5772fadf1 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/d208d2c52b652913b5eefc8ca434b0d6b757f68f Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/e3be8862d73cac833e0fb7602636c19c6cb94b11 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/e70a578487a47d7cf058904141e586684d1c3381 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/e7343fa33751cb07c1c56b666bf37cfca357130e Types: Patch
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Mar. 13, 2025

    Action Type Old Value New Value
    Added Reference https://git.kernel.org/stable/c/6bef6222a3f6c7adb6396f77f25a3579d821b09a
    Added Reference https://git.kernel.org/stable/c/e3be8862d73cac833e0fb7602636c19c6cb94b11
    Added Reference https://git.kernel.org/stable/c/e70a578487a47d7cf058904141e586684d1c3381
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Feb. 27, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    Added CWE CWE-416
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Feb. 27, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: nbd: don't allow reconnect after disconnect Following process can cause nbd_config UAF: 1) grab nbd_config temporarily; 2) nbd_genl_disconnect() flush all recv_work() and release the initial reference: nbd_genl_disconnect nbd_disconnect_and_put nbd_disconnect flush_workqueue(nbd->recv_workq) if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...)) nbd_config_put -> due to step 1), reference is still not zero 3) nbd_genl_reconfigure() queue recv_work() again; nbd_genl_reconfigure config = nbd_get_config_unlocked(nbd) if (!config) -> succeed if (!test_bit(NBD_RT_BOUND, ...)) -> succeed nbd_reconnect_socket queue_work(nbd->recv_workq, &args->work) 4) step 1) release the reference; 5) Finially, recv_work() will trigger UAF: recv_work nbd_config_put(nbd) -> nbd_config is freed atomic_dec(&config->recv_threads) -> UAF Fix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so that nbd_genl_reconfigure() will fail.
    Added Reference https://git.kernel.org/stable/c/844b8cdc681612ff24df62cdefddeab5772fadf1
    Added Reference https://git.kernel.org/stable/c/9793bd5ae4bdbdb2dde401a3cab94a6bfd05e302
    Added Reference https://git.kernel.org/stable/c/a8ee6ecde2b7bfb58c8a3afe8a9d2b848f580739
    Added Reference https://git.kernel.org/stable/c/d208d2c52b652913b5eefc8ca434b0d6b757f68f
    Added Reference https://git.kernel.org/stable/c/e7343fa33751cb07c1c56b666bf37cfca357130e
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 7.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact