CVE-2023-53330 – This CVE describes a memory leak vulnerability ... (How to Fix)

Q: What is the severity of CVE-2023-53330?

CVE-2023-53330 has a CVSS score of 5.5 (MEDIUM). This CVE describes a memory leak vulnerability in the Linux kernel's caif (Communication CPU to Application CPU Interface) subsystem. When cfctrl_linkup_request() encounters an unknown linktype or memory allocation failure, it fails to release allocated packet memory, causing gradual memory exhaustion. This affects Linux systems using the caif subsystem, typically in embedded or mobile contexts.

📋 TL;DR

This CVE describes a memory leak vulnerability in the Linux kernel's caif (Communication CPU to Application CPU Interface) subsystem. When cfctrl_linkup_request() encounters an unknown linktype or memory allocation failure, it fails to release allocated packet memory, causing gradual memory exhaustion. This affects Linux systems using the caif subsystem, typically in embedded or mobile contexts.

💻 Affected Systems

Products:

Linux Kernel

Versions: Specific affected versions not explicitly stated in CVE, but patches exist in stable kernel trees

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only vulnerable if caif subsystem is enabled and used. Many desktop/server distributions may not have caif enabled by default.

📦 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...

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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

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

🟠

Likely Case

Gradual memory consumption over time leading to performance degradation and eventual denial of service on affected systems.

🟢

If Mitigated

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

🌐 Internet-Facing: LOW - caif subsystem is typically used for internal communication between CPU cores, not exposed to external networks.

🏢 Internal Only: MEDIUM - Systems using caif for inter-processor communication could experience stability issues affecting overall system reliability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires ability to trigger cfctrl_linkup_request() with unknown linktype or cause memory allocation failure. Likely requires local access or ability to interact with caif subsystem.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in stable kernel versions via provided git commits

Vendor Advisory: https://git.kernel.org/stable/c/1dddeceb26002cfea4c375e92ac6498768dc7349

Restart Required: No

Instructions:

1. Update to a patched kernel version containing the fix commits. 2. For custom kernels, apply the patch from the provided git commits. 3. Rebuild and deploy the updated kernel.

🔧 Temporary Workarounds

Disable caif subsystem

Linux

If caif functionality is not required, disable the subsystem to eliminate the vulnerability

echo "blacklist caif" >> /etc/modprobe.d/blacklist.conf
rmmod caif

🧯 If You Can't Patch

Implement memory monitoring and alerting for kernel memory usage
Restrict access to systems using caif subsystem to trusted users only

🔍 How to Verify

Check if Vulnerable:

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

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is patched by checking for the fix commits in kernel source or verifying with vendor-specific security updates

📡 Detection & Monitoring

Log Indicators:

Kernel oom-killer messages
Increasing kernel memory usage in /proc/meminfo
System performance degradation logs

Network Indicators:

None - this is a local memory management issue

SIEM Query:

source="kernel" AND ("out of memory" OR "oom-killer" OR memory_exhaustion)

📊 Metadata

CVE ID: CVE-2023-53330

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: 0.01% exploit probability (1.2th percentile)

Published: September 16, 2025

Last Updated: January 14, 2026

🔗 References

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