CVE-2026-3622 in TL-WR841N
Summary
by MITRE • 03/26/2026
The vulnerability exists in the UPnP component of TL-WR841N v14, where improper input validation leads to an out-of-bounds read, potentially causing a crash of the UPnP service.
Successful exploitation can cause the UPnP service to crash, resulting in a Denial-of-Service condition. This vulnerability affects TL-WR841N v14 < EN_0.9.1 4.19 Build 260303 Rel.42399n (V14_260303) and < US_0.9.1.4.19 Build 260312 Rel. 49108n (V14_0304).
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Analysis
by VulDB Data Team • 03/27/2026
The vulnerability identified as CVE-2026-3622 resides within the Universal Plug and Play component of the TP-Link TL-WR841N v14 router firmware, representing a critical security flaw that undermines the device's operational integrity. This issue manifests as improper input validation within the UPnP service implementation, creating a condition where maliciously crafted input can trigger unexpected behavior in the underlying software architecture. The affected firmware versions specifically include the European and United States variants with build numbers indicating the vulnerable release cycles, making this a widespread concern across multiple regional deployments of the same hardware platform. The vulnerability's presence in the UPnP service component is particularly concerning given the service's role in facilitating network device communication and automatic port mapping.
The technical flaw constitutes an out-of-bounds read condition that occurs when the UPnP service processes incoming requests without adequate validation of input parameters. This type of vulnerability falls under the Common Weakness Enumeration category CWE-125, which describes out-of-bounds read conditions where an application attempts to read data from memory locations beyond the intended buffer boundaries. The improper input validation allows attackers to craft specific UPnP requests that cause the service to access memory regions it should not be able to reach, leading to unpredictable behavior and ultimately resulting in service termination. The vulnerability's exploitation requires minimal privileges and can be executed through standard network communication protocols, making it particularly dangerous in networked environments where UPnP services are enabled by default.
The operational impact of this vulnerability extends beyond simple service disruption, creating a potential denial-of-service condition that can render the router's UPnP functionality completely inoperative. When the UPnP service crashes, it not only prevents automatic port mapping and device discovery but also potentially affects other network services that may depend on proper UPnP operation for seamless communication. This disruption can cascade into broader network issues, particularly in home and small office environments where users may not immediately recognize that their network device has become unresponsive to automatic configuration requests. The vulnerability's ability to cause service crashes makes it particularly attractive to attackers seeking to disrupt network operations, as the impact is immediate and visible to network administrators and end users alike.
Mitigation strategies for this vulnerability should prioritize firmware updates from TP-Link to address the root cause through proper input validation implementation. Network administrators should consider disabling UPnP services entirely if they are not required for specific network configurations, as this eliminates the attack surface for exploitation. Additionally, implementing network monitoring solutions that can detect abnormal UPnP traffic patterns may help identify potential exploitation attempts before they cause service disruption. Security teams should also consider network segmentation strategies to limit the potential impact of such vulnerabilities across the broader network infrastructure. The remediation approach must align with established security frameworks and best practices for embedded system security, ensuring that similar vulnerabilities are not present in other components of the router's firmware ecosystem.