# CVE-2026-36819: Tenda W20E buffer overflow in fromSetDhcpRules

Source: https://junglewise.ai/threats/cve-2026-36819-tenda-w20e-buffer-overflow-in-fromsetdhcprules  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-36819 · Severity: info · CVSS 7.5 · Published 2026-06-09

The Tenda W20E enterprise router is vulnerable to a security flaw that can be used to crash the device. By sending a specially crafted web request to the router's management interface, an attacker can trigger a system failure, leading to a denial of service. This disrupts internet connectivity and network operations for all connected users until the device is recovered.

Technologies: [Tenda W20E](https://junglewise.ai/threats/technologies/w20e). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2026-36819 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-36819 being exploited in the wild.

**How severe is CVE-2026-36819?** Informational severity, with a CVSS score of 7.5, published 9 June 2026.

**Which products and versions are affected?** Tenda W20E v15.11.0.6.

**Is there a fix for CVE-2026-36819?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-36819 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-36819?** Check whether you run Tenda W20E at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stack-based buffer overflow exists in the Tenda W20E router firmware version v15.11.0.6. The vulnerability is located within the 'fromSetDhcpRules' function, specifically inside the 'modifyDhcpRule' sub-function. The 'bindMACAddr' HTTP parameter is retrieved via 'websGetVar' and subsequently passed to 'snprintf' with a fixed-size destination buffer of 0x2f bytes. An attacker can provide an overly long string (e.g., 888 characters) for the 'bindMACAddr' parameter to overflow the buffer. This can be exploited via a network-reachable HTTP request to the 'setDhcpRules' action, resulting in a process crash or device instability (Denial of Service).

## Affected products

- Tenda W20E v15.11.0.6

## Timeline

- 2026-03-19: other: CVE request submitted to MITRE
- 2026-06-06: disclosed: Public disclosure
- 2026-06-09: advisory: NVD published date

## References

- [https://github.com/xhh0124/SemVulLLM/tree/main/W20E/fromSetDhcpRules](https://github.com/xhh0124/SemVulLLM/tree/main/W20E/fromSetDhcpRules)

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