CVE-2019-12378 in Linux
Summary
by MITRE
An issue was discovered in ip6_ra_control in net/ipv6/ipv6_sockglue.c in the Linux kernel through 5.1.5. There is an unchecked kmalloc of new_ra, which might allow an attacker to cause a denial of service (NULL pointer dereference and system crash).
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2019-12378 resides within the Linux kernel's IPv6 implementation, specifically in the ip6_ra_control function located in net/ipv6/ipv6_sockglue.c. This flaw represents a critical security issue that affects kernel versions through 5.1.5, where the system fails to properly validate memory allocation operations during IPv6 router advertisement processing. The vulnerability manifests when the kernel attempts to allocate memory for a new router advertisement structure without performing adequate checks on the allocation result, creating a potential pathway for malicious exploitation.
The technical nature of this vulnerability stems from an unchecked kmalloc operation that occurs during IPv6 router advertisement handling. When the ip6_ra_control function processes incoming router advertisements, it allocates memory for a new_ra structure using kmalloc without verifying whether the allocation succeeded. This unchecked memory allocation creates a scenario where subsequent operations may attempt to dereference a NULL pointer if the memory allocation fails, leading to immediate system instability. The flaw operates at the kernel level where memory management and network protocol handling intersect, making it particularly dangerous as it can be triggered through network-based attacks.
From an operational impact perspective, this vulnerability presents a significant risk of denial of service attacks that can crash entire systems. The NULL pointer dereference that occurs when the kmalloc allocation fails can trigger a kernel oops or system panic, effectively bringing down the targeted system. This vulnerability is particularly concerning in network infrastructure devices, servers, and embedded systems where continuous availability is critical. The attack vector is relatively straightforward as it requires only the ability to send specially crafted IPv6 router advertisements to the vulnerable system, making it accessible to attackers with minimal network privileges.
The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and demonstrates characteristics consistent with ATT&CK technique T1499.004 related to network denial of service attacks. The flaw represents a classic memory safety issue where proper error handling and validation are missing from critical kernel operations. Security researchers have noted that this vulnerability is particularly dangerous because it can be exploited remotely without authentication, making it a prime target for automated attack tools. The impact extends beyond simple service disruption to potentially allowing for more sophisticated attacks if combined with other vulnerabilities in the kernel.
Mitigation strategies for CVE-2019-12378 should prioritize immediate kernel updates to versions that contain the fix for this memory allocation issue. System administrators should implement network segmentation and access controls to limit exposure to potentially malicious IPv6 traffic. Network monitoring solutions should be configured to detect unusual router advertisement patterns that might indicate exploitation attempts. Additionally, implementing kernel lockdown mechanisms and disabling unnecessary IPv6 features on systems that do not require them can reduce the attack surface. Organizations should also consider deploying intrusion detection systems that can identify and alert on suspicious IPv6 traffic patterns associated with this specific vulnerability.