CVE-2025-15247 is a heap-based buffer overflow vulnerability found in the snap7-rs library, an implementation used for communication with Siemens S7 PLCs (Programmable Logic Controllers). The flaw resides in the S7Client::download function within the client.rs source file. This function improperly handles input data, leading to a heap overflow condition when processing specially crafted requests. Because the vulnerability is remotely exploitable without requiring authentication or user interaction, an attacker can send malicious packets to vulnerable instances of snap7-rs to trigger the overflow. Exploitation could allow arbitrary code execution or cause a denial of service by crashing the application. The snap7-rs project uses a rolling release model, making it difficult to identify specific affected versions beyond the known commit hash. The vendor has not yet responded or issued a patch despite early notification. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges or user interaction required (PR:N/UI:N), and impacts on confidentiality, integrity, and availability rated as low to medium. Although no known exploits are currently observed in the wild, a public exploit exists, increasing the risk of active exploitation. The vulnerability is particularly concerning for industrial control systems and automation environments relying on snap7-rs for PLC communication, where stability and security are critical.

For European organizations, the impact of this vulnerability is significant, especially for those in manufacturing, energy, utilities, and critical infrastructure sectors that utilize Siemens S7 PLCs and the snap7-rs library for automation and control. Exploitation could lead to unauthorized control or disruption of industrial processes, resulting in operational downtime, safety hazards, and potential data breaches. The ability to execute code remotely without authentication increases the risk of targeted attacks or widespread exploitation if exposed to untrusted networks. This could affect the confidentiality of sensitive operational data, integrity of control commands, and availability of critical systems. Given Europe's strong industrial base, particularly in countries like Germany, France, and Italy, the threat could have cascading effects on supply chains and national infrastructure. Additionally, regulatory compliance frameworks such as NIS2 and GDPR may impose reporting and remediation obligations if this vulnerability leads to incidents.

1. Network Segmentation: Isolate systems running snap7-rs from untrusted networks and restrict access to only trusted management stations using firewalls and access control lists. 2. Intrusion Detection and Prevention: Deploy network monitoring tools to detect anomalous traffic patterns targeting the S7Client::download function or snap7-rs communication ports. 3. Runtime Protections: Utilize memory protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) on hosts running snap7-rs to mitigate exploitation impact. 4. Application Hardening: If possible, replace or wrap snap7-rs with more secure or updated libraries that have addressed this vulnerability. 5. Incident Response Preparation: Develop and test response plans for potential exploitation scenarios, including system isolation and forensic analysis. 6. Vendor Engagement: Continuously monitor for vendor patches or updates and apply them promptly once available. 7. Code Review and Custom Patching: For organizations with development capabilities, review the snap7-rs source code to identify and patch the vulnerable function proactively. 8. Limit Exposure: Avoid exposing snap7-rs services directly to the internet or untrusted environments.