CVE-2025-57636 is an OS command injection vulnerability identified in the D-Link C1 device firmware dated 2020-02-21. The vulnerability exists in the jhttpd component, specifically within the sub_47F028 function, which improperly handles the HTTP parameter "time". This improper input validation allows an attacker to inject arbitrary operating system commands via crafted HTTP requests. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). Successful exploitation could lead to limited confidentiality and integrity impacts, such as unauthorized information disclosure or modification of device settings, but does not affect availability. The CVSS base score is 6.5, categorizing it as a medium severity issue. The vulnerability is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), a common and critical class of injection flaws. No patches or known exploits in the wild have been reported as of the publication date (September 23, 2025). The affected versions are unspecified, but the reference to the 2020-02-21 firmware suggests older D-Link C1 devices are at risk. This vulnerability could be leveraged by attackers to gain unauthorized control or manipulate the device, potentially using it as a foothold for further network intrusion or lateral movement.

For European organizations, the impact of CVE-2025-57636 depends largely on the deployment scale of D-Link C1 devices within their infrastructure. These devices are typically consumer or small office network equipment, so the direct impact on large enterprise core infrastructure may be limited. However, compromised devices could serve as entry points for attackers to pivot into corporate networks, especially in small and medium-sized enterprises (SMEs) or home office environments common in Europe. Confidentiality and integrity risks include unauthorized access to device configuration, leakage of network metadata, or manipulation of device behavior. Given the lack of availability impact, denial-of-service is unlikely. The vulnerability's remote and unauthenticated nature increases the risk of exploitation by opportunistic attackers or automated scanning tools. European organizations with extensive remote workforces or distributed branch offices using D-Link C1 devices should be particularly cautious, as these devices may be exposed to the internet or less protected network segments. The absence of known exploits in the wild currently reduces immediate risk but does not preclude future exploitation, especially as details become public.

1. Immediate mitigation should include network-level controls such as firewall rules to restrict external access to the management interfaces of D-Link C1 devices, especially blocking HTTP access from untrusted networks. 2. Organizations should inventory their network devices to identify any D-Link C1 models and verify firmware versions. 3. Although no official patches are currently available, monitoring D-Link's security advisories for firmware updates addressing this vulnerability is critical. 4. If patching is not possible, consider device replacement or segmentation of vulnerable devices into isolated network zones to limit potential attacker movement. 5. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or anomaly detection for command injection patterns targeting HTTP parameters. 6. Regularly audit device configurations and logs for suspicious activity related to the "time" parameter or unexpected command execution. 7. Educate IT staff about this vulnerability to ensure rapid response if exploitation attempts are detected. 8. Implement network segmentation and zero-trust principles to minimize the impact of any compromised device.