CVE-2026-5024 Overview
CVE-2026-5024 is a stack-based buffer overflow vulnerability affecting the D-Link DIR-513 router running firmware version 1.10. The flaw resides in the formSetEmail function within /goform/formSetEmail, where the curTime argument is processed without proper bounds checking. Attackers can trigger the overflow remotely over the network with low privileges.
The exploit details have been published, increasing the risk of opportunistic attacks. D-Link no longer supports the DIR-513 product line, so no official patch will be released. Affected device owners must rely on workarounds or hardware replacement.
Critical Impact
Remote attackers can corrupt stack memory on unsupported D-Link DIR-513 routers through the formSetEmail endpoint, potentially leading to arbitrary code execution or device compromise.
Affected Products
- D-Link DIR-513 hardware router
- D-Link DIR-513 firmware version 1.10
- All deployments of the DIR-513 line (end-of-life, no longer supported)
Discovery Timeline
- 2026-03-29 - CVE-2026-5024 published to NVD
- 2026-03-30 - Last updated in NVD database
Technical Details for CVE-2026-5024
Vulnerability Analysis
The vulnerability is a stack-based buffer overflow [CWE-121] classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer) and [CWE-787] (Out-of-bounds Write). The flaw exists in the HTTP request handler formSetEmail exposed at /goform/formSetEmail on the device's web management interface.
When the router processes a request to this endpoint, it reads the user-supplied curTime parameter and copies it into a fixed-size stack buffer without validating the input length. Supplying an oversized curTime value overwrites adjacent stack memory, including saved return addresses and frame pointers.
Because embedded MIPS or ARM firmware on consumer routers typically lacks modern mitigations such as stack canaries, address space layout randomization (ASLR), and non-executable stacks, the overflow can be reliably weaponized into arbitrary code execution. Successful exploitation grants the attacker control over the router's network traffic and configuration.
Root Cause
The root cause is unsafe string handling inside formSetEmail. The function copies the attacker-controlled curTime HTTP parameter into a stack-allocated buffer using an unbounded copy operation. No length check is performed against the destination buffer size before the write.
Attack Vector
The attack is performed remotely over the network against the router's web administration interface. An authenticated session with low privileges is required, as reflected by the PR:L component of the CVSS vector. The attacker issues a crafted HTTP POST request to /goform/formSetEmail containing an oversized curTime argument to trigger the overflow.
No verified public exploit code is included in the reference set, but the technical write-up at the GitHub Vulnerability Repository documents the parameter and offset details required to reproduce the crash.
Detection Methods for CVE-2026-5024
Indicators of Compromise
- HTTP POST requests to /goform/formSetEmail containing unusually long curTime parameter values, particularly exceeding 100 bytes.
- Unexpected reboots, watchdog resets, or crash logs on DIR-513 devices following inbound web management traffic.
- Outbound connections from the router to unfamiliar hosts, indicating possible post-exploitation command-and-control activity.
Detection Strategies
- Inspect network traffic for HTTP requests targeting /goform/formSetEmail from untrusted source addresses, especially from the WAN side.
- Deploy intrusion detection signatures that flag oversized form parameters submitted to D-Link goform endpoints.
- Correlate router authentication logs with subsequent administrative form submissions to identify suspicious sequences.
Monitoring Recommendations
- Forward syslog and SNMP trap data from edge routers to a central log repository for anomaly review.
- Monitor DNS and NetFlow telemetry for traffic patterns that diverge from baseline behavior of DIR-513 devices.
- Track firmware integrity by comparing periodic configuration snapshots against a known-good baseline.
How to Mitigate CVE-2026-5024
Immediate Actions Required
- Disable remote (WAN-side) administration on all DIR-513 devices and restrict the management interface to a trusted LAN segment.
- Place affected routers behind a network segment that filters HTTP and HTTPS access to /goform/ URIs from untrusted sources.
- Plan replacement of DIR-513 hardware with a currently supported router model, since the device is end-of-life.
Patch Information
No patch is available. D-Link has confirmed the DIR-513 line is no longer supported by the maintainer, and no firmware update will be issued for version 1.10. Refer to the D-Link Security Overview and the VulDB #353908 record for ongoing status. Replacement with a supported device is the recommended long-term remediation.
Workarounds
- Change default and weak administrative credentials to reduce the risk of attackers obtaining the low-privileged access required by the CVSS vector.
- Block external access to TCP ports 80 and 443 on the router's WAN interface using upstream firewall rules.
- Disable the email notification feature in the router's web UI to reduce exposure of the vulnerable handler where supported.
- Segment IoT and consumer network equipment away from sensitive corporate assets to limit lateral movement after compromise.
# Configuration example: upstream firewall rules to restrict access to a DIR-513 management interface
# Replace <router_ip> with the LAN address of the DIR-513 and <admin_subnet> with the trusted subnet
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -s <admin_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -s <admin_subnet> -j ACCEPT
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
