CVE-2020-25221 Explained : Impact and Mitigation
Learn about CVE-2020-25221, a privilege escalation flaw in Linux kernel versions 5.7.x and 5.8.x before 5.8.7 due to incorrect reference counting, allowing attackers to trigger a refcount underflow.
A privilege escalation vulnerability in the Linux kernel versions 5.7.x and 5.8.x before 5.8.7 allows attackers to exploit incorrect reference counting, leading to a refcount underflow.
Understanding CVE-2020-25221
This CVE involves a flaw in the handling of the struct page that supports the vsyscall page, potentially triggered by specific processes.
What is CVE-2020-25221?
The vulnerability arises from improper reference counting due to gate page mishandling, impacting the vsyscall page.
The Impact of CVE-2020-25221
The vulnerability enables privilege escalation for 64-bit processes utilizing ptrace() or process_vm_readv(), identified as CID-9fa2dd946743.
Technical Details of CVE-2020-25221
The technical aspects of this CVE include:
Vulnerability Description
- Vulnerability in get_gate_page in mm/gup.c
- Incorrect reference counting leading to a refcount underflow
Affected Systems and Versions
- Linux kernel versions 5.7.x and 5.8.x before 5.8.7
Exploitation Mechanism
- Triggered by any 64-bit process capable of using ptrace() or process_vm_readv()
Mitigation and Prevention
To address CVE-2020-25221, consider the following steps:
Immediate Steps to Take
- Apply official patches and updates promptly
- Monitor vendor security advisories for relevant information
Long-Term Security Practices
- Implement the principle of least privilege
- Regularly review and update security configurations
Patching and Updates
- Update to Linux kernel version 5.8.7 or later to mitigate the vulnerability