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CVE-2025-38471

7.8 HIGH
Denial of Service

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's TLS implementation allows reading freed memory when processing network packets. This affects systems using TLS in the kernel (kTLS) with recent TCP optimizations. Attackers could potentially cause crashes or leak sensitive kernel memory.

💻 Affected Systems

Products:
  • Linux kernel
Versions: Kernel versions with specific TLS and TCP optimization changes (around 6.16.0-rc5 and related)
Operating Systems: Linux distributions using affected kernel versions
Default Config Vulnerable: ✅ No
Notes: Only vulnerable when kTLS (kernel TLS) is enabled and used. Many distributions don't enable kTLS by default.

📦 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...

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 →

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 →

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

Kernel memory corruption leading to system crash (DoS) or potential information disclosure of sensitive kernel data.

🟠

Likely Case

System instability, kernel panics, or denial of service on affected systems using kTLS.

🟢

If Mitigated

Minimal impact if systems don't use kTLS or have proper memory protection mechanisms.

🌐 Internet-Facing: MEDIUM - Requires network access and TLS connections, but exploit complexity is moderate.
🏢 Internal Only: MEDIUM - Internal systems using kTLS are vulnerable to authenticated attackers.

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ✅ No
Complexity: MEDIUM

Exploitation requires ability to send crafted TLS packets to a vulnerable system with kTLS enabled.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patches available in stable kernel trees (commits: 1f3a429c21e0e43e8b8c55d30701e91411a4df02, 4ab26bce3969f8fd925fe6f6f551e4d1a508c68b, etc.)

Vendor Advisory: https://git.kernel.org/stable/c/1f3a429c21e0e43e8b8c55d30701e91411a4df02

Restart Required: Yes

Instructions:

1. Update to patched kernel version from your distribution. 2. Reboot system. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable kTLS

linux

Disable kernel TLS support if not required

echo 0 > /proc/sys/net/tls/enabled

🧯 If You Can't Patch

  • Disable kTLS functionality if not required
  • Implement network segmentation to limit access to systems using kTLS

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if kTLS is enabled: uname -r && cat /proc/sys/net/tls/enabled

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is patched and check for absence of KASAN reports in dmesg

📡 Detection & Monitoring

Log Indicators:

  • KASAN reports in kernel logs
  • Kernel panic messages related to TLS or tls_strp

Network Indicators:

  • Unusual TLS connection patterns to systems with kTLS enabled

SIEM Query:

source="kernel" AND ("KASAN" OR "tls_strp" OR "slab-use-after-free")

📊 Metadata

CVE ID: CVE-2025-38471
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 (4.5th percentile)
Published: July 28, 2025
Last Updated: December 22, 2025

🔗 References

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