# CVE-2026-78861: Mercusys AC12 V2 hardcoded RSA private key code execution

Source: https://junglewise.ai/threats/cve-2026-78861-an-issue-in-mercusys-ac12-v2-allows-a-local-attacker-to-execute  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-05. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-78861 · Severity: info · Published 2026-10-05

The Mercusys AC12 V2 is a wireless router used in home and small office networks. The device contains a hardcoded 512-bit RSA private key that an attacker with local access can use to impersonate the device and execute arbitrary code, potentially compromising the network and any connected devices.

Technologies: [Mercusys AC12 V2](https://junglewise.ai/threats/technologies/ac12-v2). Vendors: [Mercusys](https://junglewise.ai/threats/vendors/mercusys).

## Quick answers

**Is CVE-2026-78861 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78861 being exploited in the wild.

**How severe is CVE-2026-78861?** Informational severity, published 5 October 2026.

**Which products and versions are affected?** Mercusys AC12 V2.

**Is there a fix for CVE-2026-78861?** 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-2026-78861 attacked?** It is attacked with local access.

**Am I affected by CVE-2026-78861?** Check whether you run Mercusys AC12 V2. 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

The AC12 V2 router embeds a hardcoded RSA private key in its firmware, allowing local attackers to forge cryptographic signatures or decrypt sensitive communications. The vulnerability requires local access to the device or its firmware; recovery of the private key enables arbitrary code execution with device privileges.

## Affected products

- Mercusys AC12 V2

## Timeline

- 2026-10-05: disclosed

## References

- [http://ac12.com/](http://ac12.com/)
- [http://mercusys.com/](http://mercusys.com/)

## Related threats

- [Mercusys AC12 V2 arbitrary code execution via UART interface](https://junglewise.ai/threats/cve-2026-78862-an-issue-in-mercusys-ac12-v2-allows-a-local-attacker-to-execute)
- [Mercusys AC12 V2 missing firmware encryption and secure boot](https://junglewise.ai/threats/cve-2026-78860-an-issue-in-mercusys-ac12-v2-allows-a-local-attacker-to-execute)