CVE-2026-6012 Overview
A buffer overflow vulnerability has been identified in D-Link DIR-513 firmware version 1.10. This vulnerability affects the formSetPassword function located in the /goform/formSetPassword endpoint of the POST Request Handler component. Improper handling of the curTime argument allows for memory corruption through buffer overflow. This is a remotely exploitable vulnerability, and a public exploit has been disclosed.
Critical Impact
Remote attackers can exploit this buffer overflow vulnerability to potentially execute arbitrary code or cause denial of service on affected D-Link DIR-513 routers. This vulnerability only affects products that are no longer supported by the maintainer, leaving devices permanently vulnerable.
Affected Products
- D-Link DIR-513 firmware version 1.10
- D-Link DIR-513 routers with POST Request Handler component
Discovery Timeline
- 2026-04-10 - CVE-2026-6012 published to NVD
- 2026-04-13 - Last updated in NVD database
Technical Details for CVE-2026-6012
Vulnerability Analysis
This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), indicating a fundamental flaw in how the affected function handles memory boundaries. The formSetPassword function fails to properly validate the length or content of the curTime argument before processing it, leading to a classic buffer overflow condition.
The vulnerability is remotely exploitable over the network and requires low-privileged access to the router's web interface. No user interaction is required for exploitation, making it particularly dangerous for exposed devices. The impact includes potential compromise of confidentiality, integrity, and availability of the affected system.
Root Cause
The root cause lies in the formSetPassword function within the /goform/formSetPassword endpoint. When processing POST requests, the function accepts the curTime parameter without adequate bounds checking. The lack of proper input validation allows an attacker to supply an oversized or malformed value that exceeds the allocated buffer space, corrupting adjacent memory regions.
This is a firmware-level vulnerability in an end-of-life product. D-Link has ceased support for the DIR-513, meaning no official patch will be released to address this security flaw.
Attack Vector
The attack is carried out remotely via crafted POST requests to the vulnerable /goform/formSetPassword endpoint. An attacker with network access to the router's administrative interface can manipulate the curTime parameter to trigger the buffer overflow.
The exploitation scenario involves sending a specially crafted HTTP POST request containing an oversized or malicious value in the curTime field. When the formSetPassword function processes this input, it writes beyond the intended buffer boundaries, potentially allowing the attacker to overwrite critical memory structures such as return addresses or function pointers.
For detailed technical analysis, refer to the VulDB Vulnerability Entry and the Notion Document on D-Link DIR-513.
Detection Methods for CVE-2026-6012
Indicators of Compromise
- Unusual or repeated POST requests to /goform/formSetPassword endpoint with abnormally large curTime parameter values
- Router crashes, reboots, or unexpected behavior following web interface access
- Unauthorized changes to router passwords or configurations
- Network traffic anomalies originating from the router indicating potential compromise
Detection Strategies
- Monitor HTTP traffic for POST requests targeting /goform/formSetPassword with suspicious payload sizes
- Implement intrusion detection rules to flag requests with oversized curTime parameters
- Review router logs for failed authentication attempts or unusual administrative access patterns
- Deploy network-based detection signatures for known buffer overflow exploitation attempts against D-Link devices
Monitoring Recommendations
- Enable and regularly review web server access logs on the router if available
- Implement network segmentation to limit exposure of vulnerable router management interfaces
- Use SentinelOne Singularity to monitor for post-exploitation activities on network segments containing vulnerable devices
- Establish baseline network behavior to detect anomalous traffic patterns
How to Mitigate CVE-2026-6012
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal networks only
- Disable remote management features if enabled
- Implement firewall rules to block external access to the /goform/formSetPassword endpoint
- Consider replacing the end-of-life D-Link DIR-513 with a supported router model
Patch Information
No official patch is available for this vulnerability. D-Link has discontinued support for the DIR-513 router, and the device is classified as end-of-life. Users are strongly advised to migrate to newer, supported hardware. For more information, visit the D-Link Official Website.
Workarounds
- Disable the web-based management interface entirely and use alternative configuration methods if available
- Place the router behind a firewall with strict ingress filtering to prevent unauthorized access
- Implement network access control lists (ACLs) to limit which hosts can communicate with the router's management interface
- Monitor the device for signs of compromise and be prepared to factory reset or replace if exploitation is suspected
# Firewall rule example to restrict access to management interface
# Block external access to the router management port (typically 80/443)
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
