Linux Kernel up to 5.12.12 Ethernet free_netdev 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 described as critical has been identified in Linux Kernel up to 5.12.12. Impacted is the function free_netdev of the component Ethernet. Executing a manipulation can lead to use after free. This vulnerability is tracked as CVE-2021-47235. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.12.12. It has been declared as critical. This vulnerability affects the function free_netdev of the component Ethernet. 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: net: ethernet: fix potential use-after-free in ec_bhf_remove static void ec_bhf_remove(struct pci_dev *dev) { ... struct ec_bhf_priv *priv = netdev_priv(net_dev); unregister_netdev(net_dev); free_netdev(net_dev); pci_iounmap(dev, priv->dma_io); pci_iounmap(dev, priv->io); ... } priv is netdev private data, but it is used after free_netdev(). It can cause use-after-free when accessing priv pointer. So, fix it by moving free_netdev() after pci_iounmap() calls.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2021-47235 since 04/10/2024. 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 04/10/2025).

The vulnerability scanner Nessus provides a plugin with the ID 234107 (Ubuntu 14.04 LTS / 16.04 LTS : Linux kernel vulnerabilities (USN-7429-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.4.274, 4.9.274, 4.14.238, 4.19.196, 5.4.128, 5.10.46 or 5.12.13 eliminates this vulnerability. Applying the patch db2bc3cfd2bc/1cafc540b7bf/b1ad28375509/0260916843cc/19f88ca68ccf/95deeb29d831/d11d79e52ba0/9cca0c2d7014 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 (234107). Once again VulDB remains the best source for vulnerability data.

Productinfo

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Version

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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: 234107
Nessus Name: Ubuntu 14.04 LTS / 16.04 LTS : Linux kernel vulnerabilities (USN-7429-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Kernel 4.4.274/4.9.274/4.14.238/4.19.196/5.4.128/5.10.46/5.12.13
Patch: db2bc3cfd2bc/1cafc540b7bf/b1ad28375509/0260916843cc/19f88ca68ccf/95deeb29d831/d11d79e52ba0/9cca0c2d7014

Timelineinfo

04/10/2024 🔍
05/21/2024 +41 days 🔍
05/21/2024 +0 days 🔍
04/10/2025 +324 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2021-47235 (🔍)
GCVE (CVE): GCVE-0-2021-47235
GCVE (VulDB): GCVE-100-265732

Entryinfo

Created: 05/21/2024 20:31
Updated: 04/10/2025 11:24
Changes: 05/21/2024 20:31 (57), 12/30/2024 20:16 (13), 04/10/2025 11:24 (2)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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