CVE-2025-39880 – A type confusion vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-39880?

CVE-2025-39880 has a CVSS score of 7.8 (HIGH). A type confusion vulnerability in the Linux kernel's libceph component allows reading/writing to incorrect memory locations when using the msgr2 protocol. This affects systems using Ceph distributed storage with the Linux kernel. The vulnerability can cause memory corruption leading to crashes or potential privilege escalation.

📋 TL;DR

A type confusion vulnerability in the Linux kernel's libceph component allows reading/writing to incorrect memory locations when using the msgr2 protocol. This affects systems using Ceph distributed storage with the Linux kernel. The vulnerability can cause memory corruption leading to crashes or potential privilege escalation.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions with vulnerable libceph implementation (specific versions not provided in CVE)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using Ceph distributed storage with msgr2 protocol enabled.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

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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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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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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Memory corruption leading to kernel panic, system crash, or potential privilege escalation to kernel mode.

🟠

Likely Case

System instability, crashes of Ceph-related services, or denial of service affecting storage operations.

🟢

If Mitigated

Limited impact with proper network segmentation and minimal Ceph usage.

🌐 Internet-Facing: LOW - Ceph storage clusters are typically internal infrastructure components.

🏢 Internal Only: MEDIUM - Affects internal storage infrastructure which could impact multiple services.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires access to Ceph storage network and knowledge of Ceph protocol internals.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 23538cfbeed87159a5ac6c61e7a6de3d8d4486a8, 35dbbc3dbf8bccb2d77c68444f42c1e6d2d27983, 591ea9c30737663a471b2bb07b27ddde86b020d5, 6bd8b56899be0b514945f639a89ccafb8f8dfaef, cdbc9836c7afadad68f374791738f118263c5371

Vendor Advisory: https://git.kernel.org/stable/c/23538cfbeed87159a5ac6c61e7a6de3d8d4486a8

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify Ceph services are functioning normally.

🔧 Temporary Workarounds

Disable msgr2 protocol

linux

Force Ceph to use msgr1 protocol instead of msgr2

ceph config set global ms_bind_msgr2 false
ceph config set global ms_cluster_mode crc

🧯 If You Can't Patch

Implement strict network segmentation for Ceph storage traffic
Monitor Ceph cluster logs for unusual activity or crashes

🔍 How to Verify

Check if Vulnerable:

Check kernel version and verify if Ceph is installed and using msgr2: 'ceph version' and 'ceph config show'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits and test Ceph connectivity: 'uname -r' and 'ceph status'

📡 Detection & Monitoring

Log Indicators:

Kernel oops messages
Ceph daemon crashes in /var/log/ceph/
System instability during Ceph operations

Network Indicators:

Unusual Ceph protocol traffic patterns
Connection resets between Ceph nodes

SIEM Query:

source="kernel" AND "Oops" OR source="ceph" AND ("segfault" OR "crash")

📊 Metadata

CVE ID: CVE-2025-39880

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-704

EPSS Score: 0.02% exploit probability (5.6th percentile)

Published: September 23, 2025

Last Updated: January 20, 2026

🔗 References

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