CVE-2023-53303
📋 TL;DR
A memory leak vulnerability in the Linux kernel's VCAP API when duplicating rules could allow local attackers to cause denial of service through resource exhaustion. This affects systems using the microchip VCAP network functionality with kernel unit testing enabled. The vulnerability requires local access to trigger.
💻 Affected Systems
- Linux kernel with microchip VCAP API support
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Local attacker could exhaust kernel memory leading to system instability or crash, potentially disrupting network services on affected systems.
Likely Case
Accidental triggering during development/testing causing memory leaks that degrade system performance over time.
If Mitigated
Minimal impact as the vulnerability requires specific configuration (CONFIG_VCAP_KUNIT_TEST) and local access.
🎯 Exploit Status
Requires local access and ability to trigger VCAP rule operations with kernel unit testing enabled.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commit 281f65d29d6da1a9b6907fb0b145aaf34f4e4822 or later
Vendor Advisory: https://git.kernel.org/stable/c/281f65d29d6da1a9b6907fb0b145aaf34f4e4822
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commit. 2. Recompile kernel if using custom build. 3. Reboot system to load patched kernel.
🔧 Temporary Workarounds
Disable VCAP KUNIT testing
allDisable CONFIG_VCAP_KUNIT_TEST in kernel configuration to prevent triggering the vulnerability
make menuconfig (navigate to VCAP settings and disable KUNIT testing)
make oldconfig (if using existing config)
🧯 If You Can't Patch
- Ensure CONFIG_VCAP_KUNIT_TEST is disabled in production kernels
- Restrict local access to systems using VCAP functionality
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if CONFIG_VCAP_KUNIT_TEST is enabled in kernel configurationCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes commit 281f65d29d6da1a9b6907fb0b145aaf34f4e4822 or check that memory leaks no longer occur during VCAP testing📡 Detection & Monitoring
Log Indicators:
- Kernel memory allocation failures
- System instability after VCAP operations
- Kernel oops messages related to memory
Network Indicators:
- Degraded network performance on systems using VCAP
SIEM Query:
kernel: ("memory leak" OR "kmem_cache_alloc_node" OR "vcap") AND ("kunit" OR "VCAP")