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CVE-2025-70219 is a stack-based buffer overflow vulnerability discovered in the D-Link DIR-513 router, specifically in firmware version 1.10. The flaw resides within the `goform/formDeviceReboot` endpoint of the embedded web server. This vulnerability is triggered when the device processes an HTTP POST request containing an overly long or maliciously crafted value for the `curTime` parameter. The affected function uses insecure C functions like `sprintf` to copy user-supplied data into a fixed-size buffer located on the stack without performing proper bounds checking. When the input exceeds the allocated buffer capacity, it overwrites adjacent memory regions on the stack, including critical data such as saved return addresses and local variables. An unauthenticated attacker can exploit this by sending a specially crafted request to the device’s web interface over the network. Successful exploitation allows the attacker to corrupt the program’s execution flow, potentially leading to arbitrary code execution with root privileges on the device. This can result in a full system compromise, allowing the attacker to modify device configuration, intercept network traffic, or use the router as a foothold for further attacks on the internal network. Due to the lack of any authentication requirements and the low complexity of the attack, this vulnerability is considered highly critical.
DailyCVE Form:
Platform: D-Link DIR-513
Version: 1.10
Vulnerability: Stack buffer overflow
Severity: Critical
Date: March 4, 2026
Prediction: None planned (EOL)
What Undercode Say:
Analytics:
The D-Link DIR-513 has reached its End-of-Life (EOL) status. Consequently, D-Link has officially announced that no security patches or firmware updates will be released to address this vulnerability . Analysis of the firmware shows that the Boa Webserver component handles numerous endpoints (such as /goform/formDeviceReboot, /goform/formSetWanNonLogin, and /goform/formAdvNetwork) using unsafe functions like `sprintf` and `strcpy` . The disclosure timeline began with private reporting to VulDB in July 2025, with public proof-of-concept exploits appearing in late 2025 . Given the product’s EOL status and the availability of exploit code, active scanning for vulnerable devices and potential botnet recruitment (e.g., into Mirai-like botnets) is highly probable.
Bash Commands and Analysis:
Security researchers and administrators can use the following tools and commands to assess their exposure:
Use Nmap to discover D-Link DIR-513 devices on the network
(Default web interface ports are typically 80/TCP or 8080/TCP)
nmap -p 80,8080 --open -sV --http- "D-Link DIR-513" 192.168.1.0/24
Check if the device is vulnerable by using curl to send a long string
Warning: This may crash the device. Use with extreme caution in production.
curl -X POST http://<target_ip>/goform/formDeviceReboot \
-d "curTime=$(python3 -c 'print("A" 2000)')"
Firmware extraction for analysis (if a firmware image is obtained)
Use binwalk to extract the filesystem from the firmware binary
binwalk -e DIR-513_FW_1.10.bin
Search for unsafe functions in the extracted binaries
Navigate to the extracted squashfs-root directory first
grep -r "sprintf" ./squashfs-root/usr/sbin/
grep -r "strcpy" ./squashfs-root/usr/sbin/
Exploit:
A remote attacker can exploit this vulnerability by sending a crafted HTTP POST request to the vulnerable endpoint. The exploit payload typically consists of a long string of characters (a “pattern”) to calculate the exact offset for overwriting the return address (EIP/RIP), followed by shellcode designed for the MIPS or ARM architecture (depending on the specific hardware revision). The public proof-of-concept code often leverages ROP (Return-Oriented Programming) chains to bypass any weak memory protections like non-executable stacks, ultimately executing commands such as binding a shell to a port or adding a user to the device.
Protection from this CVE:
Since the vendor will not release a patch, remediation relies entirely on mitigation strategies:
1. Isolate the Device: Immediately remove the D-Link DIR-513 from the network or place it behind a strict firewall that blocks all incoming traffic to ports 80/8080 from the WAN side.
2. Disable Remote Management: Ensure that remote administration features are turned off.
3. Network Segmentation: Place legacy IoT devices on a separate VLAN with no access to critical internal systems.
4. Replace Hardware: The definitive solution is to replace the EOL router with a currently supported model that receives regular security updates.
5. IPS/IDS Signatures: Deploy network intrusion prevention systems (e.g., Snort, Suricata) with signatures targeting the `curTime` buffer overflow pattern in HTTP POST requests to the `/goform/formDeviceReboot` URI.
Impact:
Successful exploitation allows for Remote Code Execution (RCE) with root privileges. An attacker can completely compromise the confidentiality, integrity, and availability of the device. This can lead to:
– Data Theft: Eavesdropping on or modifying network traffic passing through the router.
– Botnet Recruitment: The device can be enslaved into a botnet to launch DDoS attacks.
– Persistent Backdoor: Attackers can install malware to maintain persistent access, even after reboots.
– Lateral Movement: The compromised router can be used as a launch point to attack other devices on the internal network that are otherwise protected by the router’s firewall.
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Sources:
Reported By: nvd.nist.gov
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D-Link DIR-513, Stack Buffer Overflow, CVE-2025-70225 (Critical)