CVE-2026-25061 is an out-of-bounds write vulnerability categorized under CWE-787 found in the simsong tcpflow tool, specifically in versions up to and including 1.61. Tcpflow is a utility that demultiplexes TCP/IP packets for analysis and monitoring. The vulnerability occurs in the wifipcap component when parsing 802.11 wireless management frames, particularly the TIM (Traffic Indication Map) element. The flaw stems from performing a length check on an incorrect field, allowing a crafted 802.11 management frame with an abnormally large TIM length to cause a 1-byte out-of-bounds write beyond the boundary of the stack-allocated array `tim.bitmap[251]`. This memory corruption is limited in size but can destabilize the application, leading primarily to denial of service conditions such as crashes or unexpected behavior. While the possibility of arbitrary code execution exists due to the stack-based overflow, it has not been demonstrated or confirmed. The vulnerability can be exploited remotely without requiring any authentication or user interaction, as it involves processing of network packets. Currently, no patches or fixes have been released, and no known exploits have been observed in the wild. The vulnerability affects the core packet parsing logic of tcpflow when handling wireless frames, which may be used in environments that analyze wireless traffic or perform network forensics. The CVSS v4.0 base score is 5.5, reflecting medium severity with network attack vector, low attack complexity, no privileges or user interaction required, and limited impact on availability. The vulnerability’s scope is limited to tcpflow instances processing untrusted wireless traffic containing malformed TIM elements.

For European organizations, the primary impact of CVE-2026-25061 is the potential for denial of service attacks against tcpflow instances used in network monitoring, security analysis, or forensic investigations. Disruption of tcpflow could impair visibility into network traffic, delay incident response, and reduce situational awareness, especially in environments relying on tcpflow for wireless traffic analysis. Although code execution is not confirmed, the possibility cannot be ruled out, which would elevate the risk to critical infrastructure or sensitive environments. Organizations operating wireless networks or conducting wireless security assessments using tcpflow are at higher risk. The vulnerability could be exploited remotely by attackers sending crafted 802.11 management frames, potentially from within wireless network range or via compromised wireless infrastructure. This risk is heightened in public or semi-public wireless environments such as campuses, research institutions, or enterprise networks. The lack of available patches means organizations must rely on compensating controls until a fix is released. Overall, the impact is moderate but could escalate if exploitation techniques evolve.

1. Limit tcpflow’s exposure to untrusted wireless traffic by deploying it in controlled environments or behind network segmentation that restricts access to wireless management frames. 2. Implement strict filtering at wireless access points and network boundaries to detect and block malformed 802.11 management frames, particularly those with abnormal TIM element lengths. 3. Monitor tcpflow logs and system behavior for signs of crashes, memory corruption, or anomalous processing related to wireless frames. 4. Use alternative packet analysis tools that do not exhibit this vulnerability until patches become available. 5. Engage with the tcpflow maintainers or community to track patch releases and apply updates promptly once available. 6. Employ host-based intrusion detection systems (HIDS) to detect abnormal process terminations or suspicious memory behavior in tcpflow instances. 7. Educate network security teams about this vulnerability to increase awareness and readiness to respond to potential exploitation attempts. 8. Consider isolating tcpflow analysis systems from direct wireless interfaces, instead feeding captured traffic from secure collection points.