CVE-2025-3845 is a critical buffer overflow vulnerability identified in the markparticle WebServer version 1.0. The flaw exists in the function Buffer::HasWritten within the source file code/buffer/buffer.cpp. Specifically, improper handling and manipulation of the argument writePos_ can lead to a buffer overflow condition. This vulnerability allows an attacker to remotely trigger the overflow by sending specially crafted requests to the web server, potentially leading to memory corruption. Such memory corruption can result in arbitrary code execution, denial of service, or system instability. The vulnerability is exploitable without authentication and does not require user interaction, increasing its risk profile. Although the vulnerability has been publicly disclosed, no confirmed exploits have been observed in the wild to date. The markparticle WebServer is a niche web server product, and version 1.0 is the affected release. The vulnerability's root cause is a classic memory safety issue common in C++ applications that do not properly validate buffer boundaries before writing data. The absence of a patch or mitigation from the vendor at the time of disclosure further elevates the risk for users of this software. Given the critical nature of buffer overflows and their frequent use in remote code execution attacks, this vulnerability demands urgent attention from organizations using markparticle WebServer 1.0.

For European organizations running markparticle WebServer 1.0, this vulnerability poses a significant threat to confidentiality, integrity, and availability. Successful exploitation could allow attackers to execute arbitrary code remotely, potentially gaining full control over affected servers. This could lead to data breaches, unauthorized access to sensitive information, service disruption, or use of compromised servers as pivot points for lateral movement within networks. Critical infrastructure, government agencies, and enterprises relying on this web server for public-facing or internal applications are at heightened risk. The ease of remote exploitation without authentication increases the likelihood of attacks, especially if the server is internet-facing. The lack of observed exploits in the wild currently reduces immediate risk but does not eliminate the threat, as public disclosure often accelerates exploit development. The impact is amplified in sectors where uptime and data integrity are paramount, such as finance, healthcare, and public administration. Additionally, the vulnerability could be leveraged in targeted attacks or ransomware campaigns, given the potential for full system compromise.

1. Immediate mitigation should focus on isolating or removing markparticle WebServer 1.0 instances from internet-facing roles until a patch is available. 2. Network-level controls such as firewall rules or web application firewalls (WAFs) should be configured to restrict access to the affected servers, limiting exposure to trusted IP addresses only. 3. Employ intrusion detection/prevention systems (IDS/IPS) with updated signatures to detect anomalous traffic patterns indicative of exploitation attempts targeting buffer overflow vectors. 4. Conduct thorough inventory and asset management to identify all instances of markparticle WebServer 1.0 within the organization. 5. Monitor vendor communications closely for patches or official mitigations and apply updates promptly once released. 6. Implement runtime application self-protection (RASP) or memory protection techniques such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) on affected hosts to reduce exploitation success. 7. Review and enhance logging and monitoring to detect potential exploitation attempts early. 8. Consider migrating to alternative, more widely supported web server platforms with active security maintenance if patching is delayed or unavailable.