CVE-2026-25061 is an out-of-bounds write vulnerability classified under CWE-787 found in the tcpflow tool developed by simsong, specifically in versions up to and including 1.61. Tcpflow is a TCP/IP packet demultiplexer used for capturing and analyzing network traffic. The vulnerability exists in the wifipcap component that parses 802.11 wireless management frames. When handling the TIM (Traffic Indication Map) element, tcpflow performs a length check on an incorrect field, allowing a crafted 802.11 management frame with an excessively large TIM length to cause a 1-byte out-of-bounds write beyond the allocated buffer tim.bitmap[251]. This buffer is stack-allocated within the handle_beacon() function and related handlers. The overflow is small, limiting the immediate impact primarily to denial of service conditions such as crashes or memory corruption. However, the possibility of code execution cannot be ruled out, though no proof-of-concept exploits or active exploitation have been reported. The vulnerability can be triggered remotely without authentication or user interaction by sending malicious wireless frames. As of the publication date, no patches or fixes have been released, leaving systems vulnerable. The CVSS 4.0 base score is 5.5 (medium severity), reflecting the network attack vector, low complexity, no privileges or user interaction required, and limited impact on confidentiality and integrity but some impact on availability.

For European organizations, the primary impact of CVE-2026-25061 is the potential for denial of service on systems running vulnerable tcpflow versions, which could disrupt network traffic analysis and monitoring activities. This may affect incident response teams, network security monitoring, and forensic investigations relying on tcpflow data. Although code execution is not confirmed, if exploited, it could lead to further compromise of monitoring infrastructure, potentially allowing attackers to manipulate captured data or gain footholds in internal networks. Organizations involved in wireless network management, telecom operators, research institutions, and critical infrastructure sectors that utilize tcpflow for packet analysis are at higher risk. Disruptions could impact operational continuity and security visibility. The lack of available patches increases exposure duration, necessitating immediate mitigation efforts. Additionally, attackers could leverage this vulnerability to evade detection by causing tcpflow to crash or behave unpredictably.

Since no official patches are available, European organizations should implement the following specific mitigations: 1) Limit tcpflow exposure by restricting access to trusted wireless networks and filtering out untrusted or suspicious 802.11 management frames at network boundaries or wireless access points. 2) Deploy network intrusion detection systems (NIDS) capable of detecting anomalous or malformed 802.11 management frames indicative of exploitation attempts. 3) Run tcpflow with the least privileges possible and consider isolating it within containerized or sandboxed environments to reduce impact of potential crashes or exploitation. 4) Monitor tcpflow logs and system stability closely for signs of crashes or unusual behavior. 5) Engage with the tcpflow community or vendor to track patch releases and apply updates promptly once available. 6) As a temporary workaround, consider disabling wireless frame parsing features if feasible or replacing tcpflow with alternative tools not affected by this vulnerability. 7) Conduct regular security assessments of wireless infrastructure to identify and mitigate other potential attack vectors.