CVE-2025-40910 is a vulnerability identified in version 1.10 of the TPODER Net::IP::LPM Perl module, which is used for IP address manipulation and longest prefix match operations. The core issue stems from improper validation of IP CIDR address strings containing leading zero characters. In IP notation, leading zeros can be interpreted as octal numbers rather than decimal, which creates ambiguity. The vulnerability arises because the module does not correctly handle or normalize these leading zeros, allowing attackers to craft IP addresses that bypass access control mechanisms relying on IP-based filtering. This improper input validation falls under CWE-1287, which concerns the incorrect handling of input types leading to security weaknesses. By exploiting this, an attacker could potentially circumvent IP-based restrictions, gaining unauthorized access or evading detection in systems that use Net::IP::LPM for IP filtering or access control. Although no known exploits are reported in the wild yet, the flaw could be leveraged in environments where IP-based access control is critical, especially if the module is used in security-sensitive applications or network filtering tools.

For European organizations, this vulnerability could have significant security implications. Many enterprises and service providers in Europe rely on IP-based access control lists (ACLs) and filtering mechanisms to protect internal resources, enforce network segmentation, and restrict access to sensitive services. If these controls depend on the vulnerable Net::IP::LPM module, attackers could bypass restrictions by exploiting the leading zero parsing flaw. This could lead to unauthorized access to internal systems, data exfiltration, or lateral movement within networks. Critical sectors such as finance, healthcare, telecommunications, and government agencies, which often implement strict IP-based controls, may be particularly at risk. Additionally, the ambiguity in IP address interpretation could complicate incident response and forensic investigations, as logs might not accurately reflect the true source IP addresses. The absence of a patch at the time of disclosure increases the urgency for organizations to implement compensating controls. Overall, the vulnerability undermines the integrity of IP-based security controls, potentially exposing European organizations to elevated risks of intrusion and data breaches.

Given the lack of an official patch, European organizations should take immediate practical steps to mitigate this vulnerability. First, audit all systems and applications that utilize the Net::IP::LPM module version 1.10 to identify exposure. Where feasible, replace or upgrade the module to a version that correctly handles leading zeros once available. In the interim, implement strict input validation and normalization routines on IP addresses before they are processed by Net::IP::LPM, ensuring that leading zeros are either removed or consistently interpreted as decimal. Network administrators should review and tighten IP-based ACLs and consider supplementing them with additional authentication or authorization layers that do not solely rely on IP addresses. Monitoring and anomaly detection systems should be enhanced to flag unusual IP address formats or access patterns indicative of exploitation attempts. Finally, maintain close communication with the vendor and security communities for updates on patches or workarounds and prepare to deploy them promptly upon release.