A critical command injection vulnerability (CVE-2025-45491) has been identified in the Linksys E5600 router firmware version v1.1.0.26, posing a significant risk of remote code execution (RCE). The flaw resides in the runtime.ddnsStatus DynDNS function and is exploitable via the username parameter. With a CVSS score of 9.8 (Critical), this vulnerability allows unauthenticated attackers to execute arbitrary commands on affected devices1.
Technical Analysis of CVE-2025-45491
The vulnerability stems from improper input validation in the DynDNS service implementation. Attackers can inject malicious commands through the username field during DynDNS configuration updates. Successful exploitation grants full system access under root privileges due to the router’s Linux-based architecture. The weakness has been classified as CWE-78 (OS Command Injection)2.
Research indicates this is one of three command injection flaws recently discovered in the E5600 firmware. The other vulnerabilities (CVE-2025-45487 and CVE-2025-29227) affect different functions but share similar exploitation patterns3. Proof-of-concept exploits have been published on GitHub, including a Python script targeting the runtime.InternetConnection function4.
Impact and Affected Systems
The vulnerability affects all Linksys E5600 routers running firmware version v1.1.0.26. Given the device’s widespread use in small office/home office (SOHO) environments, the potential impact is considerable. Successful exploitation could lead to:
- Complete device compromise
- Network traffic interception
- Lateral movement to connected devices
- Persistence through firmware modification
As of May 2025, Linksys has not released an official patch for this vulnerability. The EPSS score currently stands at 0.02709, indicating relatively low exploitation likelihood in the wild5.
Mitigation Strategies
Until an official patch becomes available, organizations should implement the following workarounds:
- Disable DynDNS functionality in the router administration interface
- Restrict remote management access to trusted IP addresses only
- Segment affected routers from critical network segments
- Monitor for suspicious command execution patterns in router logs
Network administrators should monitor the Linksys security advisory page and NVD updates for patch information1. The vulnerability joins a growing list of command injection flaws affecting SOHO routers, highlighting the need for rigorous input validation in embedded device firmware.
Detection and Response
Security teams can detect potential exploitation attempts by monitoring for:
| Indicator | Detection Method |
|---|---|
| Unusual command strings in DynDNS requests | Web application firewall logs |
| Unexpected child processes from router services | Endpoint detection systems |
| Suspicious network connections from router IP | Network traffic analysis |
The GitHub repository containing PoC code provides useful signatures for detection rule development4. Organizations should prioritize reviewing router configurations and implementing strict network access controls.
Conclusion
CVE-2025-45491 represents a serious threat to Linksys E5600 router users, particularly in environments where these devices face the internet. The critical severity rating underscores the importance of prompt mitigation. This vulnerability serves as a reminder of the persistent risks associated with command injection flaws in network infrastructure devices.
Security professionals should track this vulnerability’s progression through official channels and remain vigilant for exploit attempts. The availability of public PoCs increases the likelihood of weaponization, making timely response essential for network defenders.
References
- “CVE-2025-45491 Detail,” NVD, 2025.
- “GitHub Advisory Database,” GitHub, 2025.
- “Vulmon Vulnerability Details,” Vulmon, 2025.
- “Linksys E5600 Command Injection PoC,” GitHub, 2025.
- “FIRST EPSS Scoring,” FIRST, 2025.
