"Copy Fail" (CVE-2026-31431): The Critical Linux Kernel Vulnerability Explained

This video delves into a critical Linux kernel vulnerability known as copy fail, a silent and pervasive security flaw that existed undiscovered for nine years, enabling local users with zero permissions to escalate to full root access. The presenter, Mahdi Bahmani, offers an in-depth technical walkthrough of the exploit, explaining how it manipulates the Linux kernel’s cryptographic API and memory management to overwrite system binaries in RAM, bypass security checks, and gain administrator privileges. The content is suitable for cybersecurity professionals, system administrators, and advanced Linux users interested in kernel security, exploit mechanics, and system hardening. Viewers will learn about a real-world privilege escalation exploit, the underlying technical details of the attack, and best practices for remediation through timely patching and system updates.

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https://itstorage.net/index.php/hem/newsm/785-copy-fail-cve-2026-31431-the-critical-linux-kernel-vulnerability-explained

https://itstorage.net/index.php/hem/newsm/793-dirty-frag-cve-2026-43284-cve-2026-43500-critical
Timeline Summary
• 00:00-01:28: Introduction to the copy fail vulnerability
Mati Bahmani introduces the copy fail, a nine-year-old Linux kernel vulnerability affecting all systems worldwide, capable of granting root access locally without permission. The video sets the context of severity by comparing it to previous major Linux kernel bugs.
• 01:28-04:29: Technical breakdown of the exploit code
The presenter explains the Python-based exploit implementation, detailing the use of Linux kernel crypto API and splice system call to bypass read-only file protections. Key functions and mechanisms manipulating kernel memory and the page cache are described line by line.
• 04:29-05:42: How the exploit modifies the su binary in memory
Explanation of how the exploit decompresses and injects a patch into the memory of the su binary to bypass password checks, enabling immediate root shell spawning.
• 05:42-07:27: Live demonstration of the exploit on unpatched Ubuntu system
A practical demo showcases executing the exploit, escalating privileges from a normal user to root within seconds by patching the kernel memory, then verifying root access.
• 07:27-08:50: System remediation and patching process
Shows running system update commands and rebooting to replace the vulnerable kernel with a patched version, illustrating essential remediation steps.
• 08:50-09:29: Re-testing the exploit on the patched system
Attempts to run the exploit again fail, demonstrating how the updated kernel defends by blocking unauthorized writes to read-only memory.
• 09:29-10:12: Summary and security message
Concludes by emphasizing the exploit mechanics and the critical importance of timely system updates to defend against long-hidden vulnerabilities.

Видео "Copy Fail" (CVE-2026-31431): The Critical Linux Kernel Vulnerability Explained канала Mahdi Bahmani