Service interruption via double SIT device cleanup
Published Jun 19, 2024 · Updated Aug 5, 2026
Denial of service in the Linux kernel SIT driver allows local users to interrupt service by creating a network namespace. During SIT device registration failure, sit_init_net calls ipip6_dev_free even though register_netdevice already invokes that private destructor, releasing the destination cache twice and underflowing its reference count. Exploitation requires local low-privileged access and the ability to create a network namespace; the demonstrated consequence is a kernel warning and service interruption.
Summary
What happened
Denial of service in the Linux kernel SIT driver allows local users to interrupt service by creating a network namespace. During SIT device registration failure, sit_init_net calls ipip6_dev_free even though register_netdevice already invokes that private destructor, releasing the destination cache twice and underflowing its reference count. Exploitation requires local low-privileged access and the ability to create a network namespace; the demonstrated consequence is a kernel warning and service interruption.
The record
- CVE
- CVE-2021-47588
- Published
- Jun 19, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 19, 2024CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.11.9 <4.12
- Affected versionversion=4.12
- Affected versionversion=95876855a55072572895a236b156ffb357fd5538
- Affected versionversion=cf124db566e6b036b8bcbe8decbed740bdfac8c6 <44a6c846bc3a7efe7d394bab8b2ae3b7f580e190
- Affected versionversion=cf124db566e6b036b8bcbe8decbed740bdfac8c6 <4e1797914d8f223726ff6ae5ece4f97d73f21bab
- Affected versionversion=cf124db566e6b036b8bcbe8decbed740bdfac8c6 <6f46c59e60b64620d5d386c8ee2eaa11ebe3b595
- Affected versionversion=cf124db566e6b036b8bcbe8decbed740bdfac8c6 <ad0ed314d6167b212939e3839428ba0c8bb16adb
- Affected versionversion=cf124db566e6b036b8bcbe8decbed740bdfac8c6 <e28587cc491ef0f3c51258fdc87fbc386b1d4c59
- Affected versionversion=cf124db566e6b036b8bcbe8decbed740bdfac8c6 <e56b65c1e74d7f706d74b51baba15187be2fb4b5
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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