CVE-2025-11961 is a buffer over-read vulnerability categorized under CWE-126 and CWE-122 affecting the libpcap library, specifically the pcap_ether_aton() function. This function is designed to convert a string representing a MAC-48 address into a fixed-size allocated buffer. However, the function’s input validation is insufficient and poorly documented, requiring the input string to strictly conform to supported MAC address formats. When an application calls pcap_ether_aton() with a malformed or improperly formatted MAC address string, the function may read beyond the end of the input string buffer and write beyond the bounds of the allocated output buffer. This can lead to memory corruption, potentially causing application instability or integrity issues. The vulnerability requires local access with high privileges (AV:L/PR:H), has a high attack complexity (AC:H), and does not require user interaction (UI:N). The CVSS v3.1 base score is 1.9, reflecting low severity due to limited impact scope: no confidentiality or availability impact, only potential integrity loss. No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability affects all versions of libpcap as indicated, making it relevant for any software relying on this widely used packet capture library. Given libpcap’s role in network monitoring, intrusion detection, and forensic tools, the vulnerability could be triggered by malformed input in privileged contexts, but exploitation is constrained by the need for local, high-privilege access and complex conditions.

For European organizations, the impact of CVE-2025-11961 is generally low due to the requirement for local high-privilege access and the limited scope of the vulnerability. However, organizations that deploy libpcap in critical network monitoring, security appliances, or forensic tools could experience application crashes or memory corruption, potentially disrupting network analysis or security operations. This could indirectly affect incident response capabilities or network visibility. The integrity impact, while limited, might allow attackers with local privileged access to cause denial of service or unexpected behavior in affected applications. Confidentiality and availability are not directly impacted. The vulnerability is less likely to be exploited remotely or at scale, reducing immediate risk to large enterprise networks. Nonetheless, organizations should consider the vulnerability in their risk assessments, especially those with sensitive infrastructure relying on libpcap-based tools.

1. Implement strict input validation for all MAC address strings passed to pcap_ether_aton() to ensure they conform exactly to supported MAC-48 formats before invoking the function. 2. Limit the use of pcap_ether_aton() to trusted inputs or sanitize inputs rigorously in applications using libpcap. 3. Run applications using libpcap with the least privilege necessary to reduce the risk of exploitation from local users. 4. Monitor vendor announcements and apply patches promptly once available, as no official patch is currently released. 5. Employ runtime memory protection mechanisms such as Address Space Layout Randomization (ASLR) and stack canaries to mitigate potential exploitation effects. 6. Conduct code audits and testing for any custom or third-party software using libpcap to identify and remediate unsafe usage of pcap_ether_aton(). 7. Consider isolating network monitoring tools in hardened environments to limit exposure to malformed inputs from untrusted sources.