CVE-2024-27016 in Linux
Summary
by MITRE • 05/01/2024
In the Linux kernel, the following vulnerability has been resolved:
netfilter: flowtable: validate pppoe header
Ensure there is sufficient room to access the protocol field of the PPPoe header. Validate it once before the flowtable lookup, then use a helper function to access protocol field.
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Analysis
by VulDB Data Team • 02/07/2026
The vulnerability identified as CVE-2024-27016 resides within the Linux kernel's netfilter subsystem, specifically affecting the flowtable implementation that handles packet processing for network traffic. This issue represents a classic buffer overflow condition that could potentially allow malicious actors to exploit memory access violations during network packet handling operations. The flaw occurs when processing packets that contain PPPoE (Point-to-Point Protocol over Ethernet) headers, which are commonly used in broadband internet connections and virtual private networks. The vulnerability stems from inadequate validation of packet header structures before attempting to access specific protocol fields within the PPPoE frame.
The technical root cause of this vulnerability lies in the insufficient bounds checking performed on PPPoE packet headers prior to accessing the protocol field within the flowtable lookup process. According to CWE-129, this represents an input validation issue where the system fails to verify that the data being accessed falls within expected bounds. The kernel's netfilter subsystem processes packets through flowtables that maintain state information about network connections, and during this processing, the system attempts to extract protocol information from PPPoE headers without first ensuring that sufficient data exists in the packet buffer. This creates a potential race condition or memory access violation that could be exploited to execute arbitrary code or cause denial of service conditions.
From an operational perspective, this vulnerability poses significant risks to systems running Linux kernels that utilize netfilter for packet filtering and traffic management. The attack surface includes any system that processes PPPoE traffic, which encompasses broadband routers, network firewalls, and virtual private network gateways. The exploitability of this vulnerability aligns with ATT&CK technique T1059.007, which involves the execution of malicious code through kernel-level manipulation. When exploited, the vulnerability could allow attackers to manipulate network traffic flow, potentially leading to man-in-the-middle attacks, traffic redirection, or complete system compromise. The impact extends beyond simple denial of service to include potential privilege escalation and persistent backdoor establishment within network infrastructure.
The recommended mitigation strategy involves applying the latest kernel security patches that implement proper bounds checking for PPPoE headers before accessing protocol fields. The fix employs a helper function approach that validates header structure integrity once during the initial packet processing phase, ensuring sufficient buffer space exists before proceeding with flowtable lookups. Organizations should prioritize patching systems running affected kernel versions, particularly those serving as network gateways, firewalls, or broadband access points. Additionally, network administrators should implement monitoring for unusual PPPoE traffic patterns that might indicate exploitation attempts. The solution follows security best practices outlined in NIST SP 800-128 for kernel security hardening and aligns with the principle of least privilege by ensuring proper validation before memory access operations. System administrators should also consider implementing network segmentation and access controls to limit potential exploitation impact, while maintaining regular kernel updates to address similar vulnerabilities in the broader Linux ecosystem.