CVE-2025-38481

Q: What is the severity of CVE-2025-38481?

CVE-2025-38481 has a CVSS score of 5.5 (MEDIUM). This CVE addresses a vulnerability in the Linux kernel's COMEDI_INSNLIST ioctl handling where an excessively large n_insns value could trigger a kernel warning and stack dump. The vulnerability affects systems using the COMEDI subsystem for data acquisition hardware control. Attackers with local access could potentially cause denial of service through kernel warnings.

5.5 MEDIUM

📋 TL;DR

This CVE addresses a vulnerability in the Linux kernel's COMEDI_INSNLIST ioctl handling where an excessively large n_insns value could trigger a kernel warning and stack dump. The vulnerability affects systems using the COMEDI subsystem for data acquisition hardware control. Attackers with local access could potentially cause denial of service through kernel warnings.

💻 Affected Systems

Products:

Linux kernel with COMEDI subsystem enabled

Versions: Linux kernel versions before the fix commits (specific versions vary by distribution)

Operating Systems: Linux distributions with vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if COMEDI subsystem is compiled into the kernel or loaded as a module, and user has access to COMEDI devices.

📦 What is this software?

Debian Linux by Debian

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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 attacker causes kernel warning/stack dump leading to system instability or denial of service, potentially revealing kernel memory information in stack traces.

🟠

Likely Case

Local user triggers kernel warning messages in system logs, causing minor disruption but no persistent system compromise.

🟢

If Mitigated

System returns -EINVAL error for invalid requests with no kernel warnings or memory exposure.

🌐 Internet-Facing: LOW - This requires local access to the COMEDI subsystem, which is not typically exposed over networks.

🏢 Internal Only: MEDIUM - Local users with COMEDI access could trigger warnings, but impact is limited to denial of service rather than privilege escalation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires local access and COMEDI device permissions. The vulnerability was discovered and fixed proactively.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits 08ae4b20f5e82101d77326ecab9089e110f224cc or later

Vendor Advisory: https://git.kernel.org/stable/c/08ae4b20f5e82101d77326ecab9089e110f224cc

Restart Required: Yes

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel package. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable COMEDI module

linux

Remove or blacklist COMEDI kernel module if not needed

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

Restrict COMEDI device access

linux

Limit COMEDI device file permissions to trusted users only

chmod 600 /dev/comedi*
chown root:root /dev/comedi*

🧯 If You Can't Patch

Restrict local user access to systems with COMEDI hardware
Monitor kernel logs for COMEDI-related warnings and investigate suspicious users

🔍 How to Verify

Check if Vulnerable:

Check if COMEDI module is loaded: lsmod | grep comedi. If loaded, check kernel version against patched versions.

Check Version:

uname -r

Verify Fix Applied:

After update, verify kernel version includes fix commits or test COMEDI_INSNLIST with large n_insns value returns -EINVAL.

📡 Detection & Monitoring

Log Indicators:

Kernel warning messages containing 'COMEDI_INSNLIST' or 'comedi' in dmesg or /var/log/kern.log

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("COMEDI" OR "comedi") AND ("WARNING" OR "stack dump")

📊 Metadata

CVE ID: CVE-2025-38481

CVSS v3 Score: 5.5 (MEDIUM)

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

EPSS Score: 0.01% exploit probability (2.3th percentile)

Published: July 28, 2025

Last Updated: January 7, 2026

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Debian Linux by Debian

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

Linux Kernel by Linux

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Disable COMEDI module

Restrict COMEDI device access

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export