# CVE-2025-51085: Tenda AC8V4 stack overflow in SetSysTimeCfg

Source: https://junglewise.ai/threats/cve-2025-51085-tenda-ac8v4-stack-overflow-in-setsystimecfg  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-07-24. Updated: 2026-07-05  
License: CC BY 4.0 with a link back

CVE-2025-51085 · Severity: medium · CVSS 5.3 · Published 2025-07-24

A vulnerability exists in the Tenda AC8V4 home router, a device used to provide wireless internet connectivity. An attacker can send a specially crafted request to the router's time configuration settings to cause the device to crash or become unresponsive. This could disrupt internet access for all connected users and require a manual restart of the hardware.

Technologies: [Tenda Ac8](https://junglewise.ai/threats/technologies/ac8), [Tenda Ac8 Firmware](https://junglewise.ai/threats/technologies/ac8-firmware), [Tenda AC8V4](https://junglewise.ai/threats/technologies/ac8v4). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2025-51085 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-51085 being exploited in the wild.

**How severe is CVE-2025-51085?** Medium severity, with a CVSS score of 5.3, published 24 July 2025.

**Which products and versions are affected?** Tenda AC8V4 V16.03.34.06.

**Is there a fix for CVE-2025-51085?** 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-2025-51085 attacked?** It is attacked over the network, in device firmware.

**Am I affected by CVE-2025-51085?** Check whether you run Tenda Ac8, Tenda Ac8 Firmware or Tenda AC8V4 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 (CWE-121) exists in the 'fromSetSysTime' function of the Tenda AC8V4 router firmware. When the 'timeType' parameter is set to 'sync', the application calls a sub-function (at address 004A75C0) that processes the 'timeZone' parameter. This parameter is retrieved from a POST request without length validation and is subsequently passed to a 'strcpy' call, leading to a stack overflow. A remote, unauthenticated attacker can exploit this by sending a long string in the 'timeZone' field to cause a denial-of-service (DoS) condition. Proof-of-concept code demonstrates the crash using a 2000-byte payload.

## Affected products

- Tenda AC8V4 V16.03.34.06

## Timeline

- 2025-07-24: disclosed: Initial vulnerability disclosure
- 2025-07-24: advisory: NVD publication date

## References

- [https://github.com/TL-SN/IOT/blob/main/Tenda/Tenda-AC8v4%20%20V16.03.34.06/CVE-2025-51085.md](https://github.com/TL-SN/IOT/blob/main/Tenda/Tenda-AC8v4%20%20V16.03.34.06/CVE-2025-51085.md)

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