# CVE-2026-9389: Tenda F456 buffer overflow in frmL7ImForm

Source: https://junglewise.ai/threats/cve-2026-9389-tenda-f456-buffer-overflow-in-frml7imform  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-24. Updated: 2026-05-26  
License: CC BY 4.0 with a link back

CVE-2026-9389 · Severity: high · CVSS 8.8 · Published 2026-05-24

A security vulnerability exists in the Tenda F456 router, a device used to provide internet connectivity for homes and small offices. An attacker can exploit this flaw to crash the router or potentially take full control of the device. This could lead to a complete loss of internet access or the interception of network traffic.

Technologies: [Tenda F456](https://junglewise.ai/threats/technologies/f456). Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2026-9389 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-9389 being exploited in the wild.

**How severe is CVE-2026-9389?** High severity, with a CVSS score of 8.8, published 24 May 2026.

**Which products and versions are affected?** Tenda F456 1.0.0.5.

**Is there a fix for CVE-2026-9389?** 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-2026-9389 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-9389?** Check whether you run Tenda F456 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 vulnerability exists in the 'httpd' service of Tenda F456 firmware version 1.0.0.5. The flaw is located within the 'frmL7ImForm' function in the '/goform/L7Im' component. The vulnerability is caused by the unsafe use of 'sprintf' when processing the 'page' parameter, which lacks proper length validation before being copied into a fixed-size stack buffer. A remote attacker with low privileges can exploit this by sending a specially crafted POST request, potentially leading to remote code execution (RCE) or a denial of service (DoS). Public exploit code (PoC) has been disclosed.

## Affected products

- Tenda F456 1.0.0.5

## Timeline

- 2026-05-24: disclosed: Public disclosure of the vulnerability and PoC.
- 2026-05-24: advisory

## References

- [https://github.com/Litengzheng/vuldb_new/blob/main/F456/vul_2/README.md](https://github.com/Litengzheng/vuldb_new/blob/main/F456/vul_2/README.md)
- [https://vuldb.com/submit/813444](https://vuldb.com/submit/813444)
- [https://vuldb.com/vuln/365352](https://vuldb.com/vuln/365352)
- [https://vuldb.com/vuln/365352/cti](https://vuldb.com/vuln/365352/cti)
- [https://www.tenda.com.cn/](https://www.tenda.com.cn/)

## Related threats

- [A vulnerability was found in Tenda F456 1.0.0.5. This impacts the function FromWriteFacMac of the file…](https://junglewise.ai/threats/cve-2026-7102-a-vulnerability-was-found-in-tenda-f456-1-0-0-5-this-impacts-the)
- [Tenda F456 buffer overflow in fromWrlclientSet](https://junglewise.ai/threats/cve-2026-7101-tenda-f456-buffer-overflow-in-fromwrlclientset)
- [A flaw has been found in Tenda F456 1.0.0.5. The impacted element is the function fromNatlimitof of the file…](https://junglewise.ai/threats/cve-2026-7100-a-flaw-has-been-found-in-tenda-f456-1-0-0-5-the-impacted-element)
- [A vulnerability was detected in Tenda F456 1.0.0.5. The affected element is the function formQuickIndex of the file…](https://junglewise.ai/threats/cve-2026-7099-a-vulnerability-was-detected-in-tenda-f456-1-0-0-5-the-affected)
- [A security vulnerability has been detected in Tenda F456 1.0.0.5. Impacted is the function fromDhcpListClient of the…](https://junglewise.ai/threats/cve-2026-7098-a-security-vulnerability-has-been-detected-in-tenda-f456-1-0-0-5)