CVE-2025-29843 identifies a path traversal vulnerability in Synology Router Manager (SRM) version 1.3, specifically within the FileStation thumb CGI component. This vulnerability arises from improper limitation of pathname inputs, allowing authenticated remote users to bypass directory restrictions and read or write image files outside the intended directory boundaries. The flaw is exploitable remotely over the network without user interaction but requires valid user credentials (low privilege). The vulnerability impacts confidentiality and integrity by enabling unauthorized access and modification of image files, which could be leveraged for further attacks or data leakage. The CVSS 3.1 base score is 5.4 (medium), reflecting network attack vector, low attack complexity, required privileges, no user interaction, and limited impact on confidentiality and integrity without availability impact. No public exploits have been reported yet, but the vulnerability is published and should be addressed promptly. The affected product, Synology SRM, is widely used in small to medium enterprises and home networks for router management and file services, making the vulnerability relevant for environments relying on these devices for network and file management. The lack of a patch link suggests that a fix may be pending or recently released, so monitoring Synology advisories is critical.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality and integrity of data managed via Synology SRM devices. Unauthorized read/write access to image files could lead to exposure of sensitive visual data or insertion of malicious files that may facilitate further compromise. Organizations using SRM in critical infrastructure or business environments may face risks of data leakage or tampering. Since the vulnerability requires authentication, the risk is higher in environments with weak credential management or where attackers can obtain valid user credentials through phishing or other means. The lack of availability impact reduces the risk of service disruption but does not eliminate the threat of stealthy data compromise. Given the widespread use of Synology devices in Europe, especially in small and medium enterprises, the vulnerability could be exploited for lateral movement or espionage if left unmitigated.

1. Apply official patches from Synology as soon as they are released to address CVE-2025-29843. 2. Restrict access to the FileStation interface and the SRM management console to trusted networks and users only, using network segmentation and firewall rules. 3. Enforce strong authentication policies, including multi-factor authentication (MFA), to reduce the risk of credential compromise. 4. Monitor logs for unusual file access or modification activities, particularly related to image files handled by FileStation. 5. Disable or limit the use of the thumb CGI component if not required, to reduce the attack surface. 6. Educate users on phishing and credential security to prevent unauthorized access. 7. Regularly audit SRM devices for firmware versions and configuration compliance. 8. Consider deploying intrusion detection systems (IDS) to detect exploitation attempts targeting this vulnerability.