CVE-2010-2495 in Linux
Summary
by MITRE
The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does not properly validate certain values associated with an interface, which allows attackers to cause a denial of service (NULL pointer dereference and OOPS) or possibly have unspecified other impact via vectors related to a routing change.
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Analysis
by VulDB Data Team • 09/24/2021
The vulnerability identified as CVE-2010-2495 resides within the Linux kernel's Layer 2 Tunneling Protocol implementation, specifically in the pppol2tp_xmit function located in drivers/net/pppol2tp.c. This flaw affects kernel versions prior to 2.6.34 and represents a critical security issue that demonstrates poor input validation practices in network protocol handling. The vulnerability stems from insufficient validation of interface-related parameters during the transmission process, creating a pathway for malicious exploitation that can result in system instability and potential privilege escalation.
The technical flaw manifests when the pppol2tp_xmit function fails to properly validate certain interface values during routing changes, leading to a NULL pointer dereference condition that triggers an OOPS (Oops, an unexpected kernel error) message. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions, and represents a classic example of improper input validation in kernel space code. The vulnerability is particularly dangerous because it can be triggered through legitimate network routing operations, making it difficult to distinguish between normal system behavior and malicious exploitation attempts.
Operationally, this vulnerability presents significant risks to systems relying on L2TP tunneling for network connectivity, particularly in enterprise environments where such protocols are commonly used for remote access and virtual private network implementations. The denial of service impact can disrupt network connectivity for extended periods, potentially affecting business continuity and network availability. While the primary impact is denial of service, the unspecified other impacts referenced in the CVE description suggest potential for more severe consequences including privilege escalation or information disclosure, which would align with the ATT&CK technique T1068 which covers local privilege escalation through kernel vulnerabilities.
Mitigation strategies for CVE-2010-2495 require immediate kernel version updates to 2.6.34 or later, as this represents the most effective solution to address the underlying validation flaw. Organizations should also implement network monitoring to detect anomalous routing changes that might trigger the vulnerability, while maintaining comprehensive system logging to track potential exploitation attempts. Additionally, security teams should consider implementing network segmentation to limit the potential impact of successful exploitation and ensure that L2TP services are properly configured with appropriate access controls to minimize the attack surface. The vulnerability serves as a reminder of the critical importance of thorough input validation in kernel space code and the potential consequences of inadequate security testing for network protocol implementations.