CVE-2025-38620 – This is a use-after-free vulnerability in the L... (How to Fix)

Q: What is the severity of CVE-2025-38620?

CVE-2025-38620 has a CVSS score of 7.8 (HIGH). This is a use-after-free vulnerability in the Linux kernel's zoned loop device (zloop) driver that allows attackers with local access to potentially execute arbitrary code or crash the system. It affects Linux systems using zoned loop devices, primarily servers and workstations with specific storage configurations.

📋 TL;DR

This is a use-after-free vulnerability in the Linux kernel's zoned loop device (zloop) driver that allows attackers with local access to potentially execute arbitrary code or crash the system. It affects Linux systems using zoned loop devices, primarily servers and workstations with specific storage configurations.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not specified in CVE, but patches exist in stable kernel trees

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when zoned loop devices (zloop) are configured and in use

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to kernel-level code execution leading to complete system compromise

🟠

Likely Case

Kernel panic or system crash causing denial of service

🟢

If Mitigated

No impact if zoned loop devices are not in use or kernel is patched

🌐 Internet-Facing: LOW - Requires local access to exploit

🏢 Internal Only: MEDIUM - Local users or compromised accounts could exploit this vulnerability

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires local access and knowledge of zloop device operations

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in stable kernel commits 765761851d89c772f482494d452e266795460278 and c7c87046b41a9ef28ee7ac476c369da5b5228bc5

Vendor Advisory: https://git.kernel.org/stable/c/765761851d89c772f482494d452e266795460278

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix. 2. Check with your distribution for specific kernel updates. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Disable zoned loop devices

linux

Prevent loading of zloop module to mitigate vulnerability

echo 'blacklist zloop' >> /etc/modprobe.d/blacklist.conf
rmmod zloop

🧯 If You Can't Patch

Disable or remove zoned loop device configurations
Restrict local user access to systems using zloop devices

🔍 How to Verify

Check if Vulnerable:

Check if zloop module is loaded: lsmod | grep zloop

Check Version:

uname -r

Verify Fix Applied:

Check kernel version against patched versions from stable kernel trees

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
KASAN use-after-free error messages in dmesg
System crash reports

Network Indicators:

None - local exploitation only

SIEM Query:

Search for 'KASAN use-after-free' or 'BUG KASAN' in kernel logs

📊 Metadata

CVE ID: CVE-2025-38620

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-416

EPSS Score: 0.02% exploit probability (4.2th percentile)

Published: August 22, 2025

Last Updated: November 26, 2025

🔗 References

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