CVE-2026-17250 in TL-MR6400
Summary
by MITRE • 08/21/2026
A stack-based buffer overflow vulnerability exists in the firmware update functionality of TL-MR6400 v7 due to unsafe processing of attacker-controlled metadata within a firmware image.
Successful exploitation may allow an authenticated attacker to trigger memory corruption and execute arbitrary code on the affected device.
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability identified in the TP-Link TL-MR6400 router, specifically version v7, represents a critical security flaw rooted in improper input validation within the firmware update mechanism. This stack-based buffer overflow occurs when the system processes metadata embedded within a firmware image file submitted by an attacker. The core technical failure lies in the lack of rigorous bounds checking during the parsing and handling of this metadata. When the device receives a specially crafted firmware package, it allocates a fixed-size buffer on the call stack to store specific fields from the update header or manifest. However, the processing logic fails to verify that the length of the incoming data does not exceed the allocated memory space. Consequently, if an attacker constructs a firmware image with metadata containing oversized strings or binary payloads, the write operation proceeds beyond the boundaries of the designated buffer, overwriting adjacent stack memory locations.
This type of vulnerability is classically categorized under CWE-121, which denotes a stack-based buffer overflow resulting from copying user-controlled input to a fixed-size buffer without adequate size verification. The exploitation vector for this flaw requires authentication on the device's management interface, as the firmware update functionality typically demands administrative privileges to initiate a flash process. Despite this requirement, the presence of an authenticated attacker significantly lowers the barrier to entry compared to remote unauthenticated exploits. Once inside the system boundary, the adversary can craft a malicious firmware file where the metadata section is engineered to contain shellcode or return-oriented programming (ROP) gadgets designed to hijack the instruction pointer. By overwriting critical stack variables such as the saved return address, function pointers, or frame pointers, the attacker gains control over the execution flow of the vulnerable process responsible for handling the update.
The operational impact of successfully exploiting this vulnerability is severe, leading directly to arbitrary code execution with the privileges of the affected service, which often runs with root-level access on embedded Linux devices like routers. This compromise allows the adversary to install persistent backdoors, exfiltrate sensitive network configuration data, or pivot into other segments of the local area network. From a threat intelligence perspective, this attack pattern aligns with MITRE ATT&CK techniques related to privilege escalation and command-line interface execution via binary exploitation. The attacker can leverage the compromised router as a foothold for further lateral movement, potentially disrupting internet connectivity for all connected devices or using the device's resources for cryptomining or distributed denial-of-service attacks against external targets.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary defense is to apply the latest firmware patches released by TP-Link that specifically correct the buffer handling logic in the update utility, ensuring strict length validation before memory allocation occurs. In environments where patching is delayed or unavailable, network segmentation should be enforced to restrict access to the router's management interface exclusively from trusted IP addresses and VLANs. Additionally, implementing strong password policies and disabling remote administration features can reduce the attack surface available to potential adversaries. Future firmware development processes for embedded devices must integrate static analysis tools and fuzz testing specifically targeting input parsing routines to detect buffer overflow conditions before deployment, thereby preventing similar vulnerabilities in subsequent hardware revisions.