CVE-2025-38616 – A Linux kernel TLS vulnerability occurs when da... (How to Fix)

Q: What is the severity of CVE-2025-38616?

CVE-2025-38616 has a CVSS score of 7.1 (HIGH). A Linux kernel TLS vulnerability occurs when data is unexpectedly removed from the TCP socket receive queue while TLS is processing it, causing TLS to read out-of-bounds memory. This affects systems using kernel TLS with specific socket reading patterns. The vulnerability can lead to undefined behavior including potential kernel crashes or data corruption.

📋 TL;DR

A Linux kernel TLS vulnerability occurs when data is unexpectedly removed from the TCP socket receive queue while TLS is processing it, causing TLS to read out-of-bounds memory. This affects systems using kernel TLS with specific socket reading patterns. The vulnerability can lead to undefined behavior including potential kernel crashes or data corruption.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific kernel versions containing the vulnerable TLS code (exact range depends on distribution backports)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only affects systems with kernel TLS enabled and using specific socket reading patterns (zerocopy or pre-TLS installation readers).

📦 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...

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 crash leading to denial of service, potential memory corruption that could be leveraged for privilege escalation or remote code execution.

🟠

Likely Case

Denial of service through kernel panic or system instability, potential data corruption in TLS streams.

🟢

If Mitigated

TLS connection errors or termination without system compromise if proper error handling is implemented.

🌐 Internet-Facing: MEDIUM - Requires specific TLS configuration and socket reading patterns, but affects network-facing services.

🏢 Internal Only: LOW - Requires local access and specific socket manipulation to trigger.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires specific timing and socket manipulation, making reliable exploitation difficult.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel commits: 2fb97ed9e2672b4f6e24ce206ac1a875ce4bcb38, 6db015fc4b5d5f63a64a193f65d98da3a7fc811d, db3658a12d5ec4db7185ae7476151a50521b7207, eb0336f213fe88bbdb7d2b19c9c9ec19245a3155, f1fe99919f629f980d0b8a7ff16950bffe06a859

Vendor Advisory: https://git.kernel.org/stable/c/2fb97ed9e2672b4f6e24ce206ac1a875ce4bcb38

Restart Required: Yes

Instructions:

1. Update to patched kernel version from your distribution. 2. Reboot system to load new kernel. 3. Verify kernel version matches patched release.

🔧 Temporary Workarounds

Disable kernel TLS

linux

Disable kernel TLS module to prevent exploitation

modprobe -r tls
echo 'blacklist tls' >> /etc/modprobe.d/blacklist-tls.conf

🧯 If You Can't Patch

Disable kernel TLS functionality in applications
Implement network segmentation to limit exposure

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if TLS module is loaded: lsmod | grep tls && uname -r

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated beyond vulnerable commits and TLS module functions normally

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
TLS handshake failures
Socket error messages

Network Indicators:

Unexpected TLS connection resets
Abnormal TLS session termination

SIEM Query:

source="kernel" AND ("panic" OR "Oops" OR "BUG") AND ("tls" OR "TLS")

📊 Metadata

CVE ID: CVE-2025-38616

CVSS v3 Score: 7.1 (HIGH)

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

CWE: CWE-125

EPSS Score: 0.02% exploit probability (2.6th percentile)

Published: August 22, 2025

Last Updated: November 26, 2025

🔗 References

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🔗 Related Vulnerabilities

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