CVE-2025-70240 is a critical (CVSS 9.8) stack buffer overflow in the D-Link DIR-513 router, firmware v1.10. The flaw sits in the formSetWAN_Wizard51 web handler and is reached through the curTime parameter. The record names no fixed version, so check the D-Link security bulletin and limit access to the admin interface.
What's affected
The record lists the D-Link DIR-513 and its firmware, version 1.10. It names no fixed version and no patched firmware.
Three other CVEs describe the same bug class in sibling handlers of the same router: CVE-2025-70239, CVE-2025-70241, CVE-2025-70245. Treat them as one problem when you plan the response.
How to check if you're exposed
This is a router, so there is no package manager command. Use the device itself.
- Log in to the admin page and read the model and firmware version. A DIR-513 on firmware 1.10 matches the record.
- Open the D-Link security bulletin page and the regional DIR-513 support page and look for an entry for this model.
- Check whether the web admin interface is reachable from the internet or from guest networks.
What to do now
- Confirm whether any DIR-513 units are in use, including at branch sites and homes of remote staff.
- Read the D-Link bulletin and support pages for this model. If a fixed firmware exists, install it. The record does not say one does, so do not assume.
- Turn off remote administration and keep the admin page reachable only from a trusted management network.
- If the vendor lists the model as no longer supported, plan to replace it. A router with an unpatched memory bug in its web interface should not sit on the edge of a network.
- Add the device to your asset inventory so the other three CVEs are tracked with it.
Why it matters
A stack buffer overflow happens when code copies input into a fixed size buffer on the stack without checking its length. The curTime value here is attacker supplied input to a web form handler, and the CVSS vector says no login and no user interaction are needed over the network. The weakness classes are CWE-121 (stack-based buffer overflow) and CWE-787 (out-of-bounds write).
The impact scores are high for confidentiality, integrity and availability, because memory corruption in a router service can in the worst case give control of the device. The record does not say the bug is exploited in the wild, and it is not in the CISA KEV list.
Quick check
Is CVE-2025-70240 the only overflow in this router?
No. Related CVEs (CVE-2025-70239, CVE-2025-70241, CVE-2025-70245) describe the same curTime weakness in other handlers, so fixing one means checking the rest.
If you want a quick look at your own dependencies, the free in-browser scan at gold.safeguard.sh/scan needs no repository access.
Sources
Referenced by the CVE record (not independently fetched for this guide):
- https://github.com/akuma-QAQ/CVEreport/tree/main/D-link/CVE-2025-70240
- https://www.dlink.com.cn/techsupport/ProductInfo.aspx?m=DIR-513
- https://www.dlink.com/en/security-bulletin/
Last reviewed: 19 October 2026.
