CVE-2023-53489 – A memory leak vulnerability in the Linux kernel... (How to Fix)

Q: What is the severity of CVE-2023-53489?

CVE-2023-53489 has a CVSS score of 5.5 (MEDIUM). A memory leak vulnerability in the Linux kernel's TCP/UDP implementation occurs when using zero-copy sockets with TX timestamping. This causes kernel memory exhaustion over time when applications repeatedly create and close such sockets. Any Linux system using zero-copy sockets with timestamping is affected.

📋 TL;DR

A memory leak vulnerability in the Linux kernel's TCP/UDP implementation occurs when using zero-copy sockets with TX timestamping. This causes kernel memory exhaustion over time when applications repeatedly create and close such sockets. Any Linux system using zero-copy sockets with timestamping is affected.

💻 Affected Systems

Products:

Linux kernel

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

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when applications use both SO_ZEROCOPY and SO_TIMESTAMPING socket options together. Requires specific application behavior to trigger.

📦 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 →

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

Sustained exploitation could lead to kernel memory exhaustion, causing system instability, denial of service, or kernel panic.

🟠

Likely Case

Memory leaks gradually consume kernel memory, potentially leading to performance degradation or system crashes over time.

🟢

If Mitigated

With proper monitoring and memory limits, impact is limited to performance issues rather than complete system failure.

🌐 Internet-Facing: MEDIUM - Requires specific socket configuration (SO_ZEROCOPY + SO_TIMESTAMPING) which is less common in internet-facing services.

🏢 Internal Only: MEDIUM - Internal applications using zero-copy sockets with timestamping could trigger the vulnerability.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

The syzkaller report includes reproducible code. Exploitation requires local access or ability to run code that creates vulnerable socket configurations.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions with commits: 1f69c086b20e27763af28145981435423f088268, 230a5ed7d813fb516de81d23f09d7506753e41e9, 281072fb2a7294cde7acbf5375b879f40a8001b7, 30290f210ba7426ff7592fe2eb4114b1b5bad219, 426384dd4980040651536fef5feac4dcc4d7ee4e

Vendor Advisory: https://git.kernel.org/stable/c/1f69c086b20e27763af28145981435423f088268

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.

🔧 Temporary Workarounds

Disable zero-copy sockets with timestamping

linux

Avoid using SO_ZEROCOPY and SO_TIMESTAMPING socket options together in applications

Monitor kernel memory usage

linux

Implement monitoring for kernel memory leaks and restart affected services

watch -n 5 'cat /proc/meminfo | grep -E "Slab|SReclaimable|SUnreclaim"'

🧯 If You Can't Patch

Restrict applications from using SO_ZEROCOPY and SO_TIMESTAMPING together
Implement memory usage limits and automatic service restart when memory thresholds are exceeded

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if applications use both SO_ZEROCOPY and SO_TIMESTAMPING socket options

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits and test with the syzkaller reproduction code

📡 Detection & Monitoring

Log Indicators:

Kernel oom-killer messages
System instability logs
Application socket creation failures

Network Indicators:

Unusual socket creation patterns with specific options

SIEM Query:

source="kernel" AND ("oom" OR "memory leak" OR "slab")

📊 Metadata

CVE ID: CVE-2023-53489

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

CWE: CWE-401

EPSS Score: 0.02% exploit probability (5.1th percentile)

Published: October 1, 2025

Last Updated: January 21, 2026

🔗 References

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