Linux Kernel up to 5.12.2 ACPI cm_write 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 5.12.2. It has been declared as critical. Affected is the function cm_write of the component ACPI. The manipulation results in use after free. This vulnerability is identified as CVE-2021-46966. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 5.12.2 (Operating System). Affected is the function cm_write of the component ACPI. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ACPI: custom_method: fix potential use-after-free issue In cm_write(), buf is always freed when reaching the end of the function. If the requested count is less than table.length, the allocated buffer will be freed but subsequent calls to cm_write() will still try to access it. Remove the unconditional kfree(buf) at the end of the function and set the buf to NULL in the -EINVAL error path to match the rest of function.

The weakness was released 02/27/2024. The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2021-46966. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/17/2025).

The vulnerability scanner Nessus provides a plugin with the ID 250166 (Linux Distros Unpatched Vulnerability : CVE-2021-46966), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.4.269, 4.9.269, 4.14.233, 4.19.191, 5.4.118, 5.10.36, 5.11.20, 5.12.3 or 5.13 eliminates this vulnerability. Applying the patch 1d53ca5d1310/8b04d57f30ca/90575d1d9311/a5b26a2e362f/72814a94c38a/62dc2440ebb5/f16737caf41f/b7a5baaae212/e483bb9a991b 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 vulnerability database at Tenable (250166). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

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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: 250166
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-46966

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Kernel 4.4.269/4.9.269/4.14.233/4.19.191/5.4.118/5.10.36/5.11.20/5.12.3/5.13
Patch: 1d53ca5d1310/8b04d57f30ca/90575d1d9311/a5b26a2e362f/72814a94c38a/62dc2440ebb5/f16737caf41f/b7a5baaae212/e483bb9a991b

Timelineinfo

02/27/2024 🔍
02/27/2024 +0 days 🔍
02/27/2024 +0 days 🔍
08/17/2025 +537 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2021-46966 (🔍)
GCVE (CVE): GCVE-0-2021-46966
GCVE (VulDB): GCVE-100-254946

Entryinfo

Created: 02/27/2024 20:07
Updated: 08/17/2025 09:32
Changes: 02/27/2024 20:07 (42), 03/14/2024 17:04 (1), 12/06/2024 19:02 (27), 08/17/2025 09:32 (2)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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