Mercusys AC12 UART Serial Interface privileges management

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.8$0-$5k1.65

Summaryinfo

A vulnerability was found in Mercusys AC12. It has been declared as very critical. The affected element is an unknown function of the component UART Serial Interface. Such manipulation leads to privileges management. This vulnerability is traded as CVE-2026-78862. An attack has to be approached locally. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Mercusys AC12 (version now known). Affected by this issue is some unknown processing of the component UART Serial Interface. The manipulation with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

An issue in Mercusys AC12 V2 allows a local attacker to execute arbitrary code via the UART serial interface on the printed circuit board (PCB)

This vulnerability is handled as CVE-2026-78862 since 08/25/2026. The exploitation is known to be easy. The attack needs to be approached locally. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/05/2026). The MITRE ATT&CK project declares the attack technique as T1068.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

Name

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.8

VulDB Base Score: 8.8
VulDB Temp Score: 8.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Privileges management
CWE: CWE-269 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

08/25/2026 CVE reserved
10/05/2026 +41 days Advisory disclosed
10/05/2026 +0 days VulDB entry created
10/05/2026 +0 days VulDB entry last update

Sourcesinfo

Status: Not defined

CVE: CVE-2026-78862 (🔒)
GCVE (CVE): GCVE-0-2026-78862
GCVE (VulDB): GCVE-100-413804

Entryinfo

Created: 10/05/2026 22:29
Changes: 10/05/2026 22:29 (50)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Interested in the pricing of exploits?

See the underground prices here!