# Yadea T5 E-Bikes Vulnerable to Wireless Relay Attacks—Firmware Update Needed


## The Threat


Yadea, a leading Chinese manufacturer of electric bicycles, has disclosed a critical wireless security flaw in its popular T5 Electric Bicycle model that could allow attackers to unlock and commandeer bikes without the owner's key fob. The vulnerability, tracked as CVE-2025-70994, stems from a weak authentication mechanism in the bike's wireless locking system that fails to properly validate key fob signals, making it susceptible to signal forgery attacks.


The weakness resides in how the T5's keyless entry system authenticates commands from the remote key fob. An attacker positioned within wireless range can intercept legitimate transmissions from an owner's key fob, analyze the signal structure, and then replay or forge similar signals to unlock the bicycle and disable its motor controls. This attack requires no sophisticated equipment—standard software-defined radio (SDR) tools commonly available in the cybersecurity community can replicate the attack within minutes of reconnaissance.


While Yadea has not publicly announced active exploitation of this vulnerability in the wild, the weakness represents a significant practical risk to the millions of e-bike users worldwide who rely on wireless locking systems as their primary theft deterrent. Given that e-bikes typically cost between $800 and $3,000, the financial incentive for theft is substantial, and the technical barrier to exploitation is low. Security researchers have repeatedly demonstrated similar wireless vulnerabilities in consumer vehicles and IoT devices, making this attack vector well-understood and easily adaptable.


## Severity and Impact


| Aspect | Details |

|--------|---------|

| CVE Identifier | CVE-2025-70994 |

| CVSS v3.1 Score | 7.3 (HIGH) |

| CVSS Vector String | CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H |

| Attack Vector | Adjacent Network (wireless range required) |

| Attack Complexity | Low—no specialized privileges needed |

| Privileges Required | None |

| User Interaction | Required (attacker must intercept a legitimate transmission) |

| Confidentiality Impact | None |

| Integrity Impact | High (bike can be unlocked and stolen) |

| Availability Impact | High (loss of bike function and control) |

| CWE Classification | CWE-1390: Weak Authentication |

| Exploitability | Not remotely exploitable; requires local/adjacent proximity |

| Public Exploits | None confirmed as of publication date |


The high CVSS score of 7.3 reflects the practical impact: a successful attack results in complete loss of bike control and enables theft. The requirement for user interaction (the attacker must intercept a transmission) lowers the score slightly, but this represents a minor hurdle given that owners regularly use their key fobs throughout the day.


## Affected Products


The following Yadea products are confirmed affected:


  • Yadea T5 Electric Bicycle — all versions (vers:all/*)

    • Users should verify their bike's model number and firmware version against the affected product designation above. Yadea has not released an official product security advisory with more granular version information, and the vendor has not coordinated with CISA regarding remediation timelines or firmware patches.


    ## Mitigations


    ### Immediate Actions


    Given that Yadea did not respond to CISA's coordination attempts and has not released a firmware patch, users have limited vendor-provided options. However, the following steps can reduce theft risk:


    Use Physical Locks as Primary Security

    Do not rely solely on the wireless locking mechanism. Users should employ a heavy-duty U-lock or cable lock as a secondary (or primary) theft deterrent. This physically prevents attackers from riding away with the bike, even if the wireless system is compromised. Secure both the frame and wheels to an immovable object whenever the bike is unattended.


    Keep the Bike in Secure Storage

    When not in use, store the T5 indoors in a garage, shed, or secure building rather than leaving it outdoors overnight. Outdoor parking significantly increases theft risk, particularly if the bike is locked only wirelessly.


    Minimize Key Fob Transmission Exposure

    Reduce the number of times you unlock the bike in public spaces. Avoid using the key fob in crowded areas or high-theft neighborhoods where attackers may be actively intercepting signals. Store the key fob away from the bike when parked to prevent relay attacks.


    Monitor for Suspicious Activity

    Check for signs of tampering, such as loose components, damaged seals, or unexpected battery drain. Modern theft techniques sometimes involve physical components being attached to the bike for tracking or unlocking.


    ### Vendor and Manufacturer Recommendations


    Yadea users are encouraged to:


    1. Contact Yadea directly via their support portal at https://yadea.com/contact-us to inquire about firmware updates and security patches. Request that the company provide a public security advisory and timeline for remediation.


    2. Register devices with Yadea (if a registration system exists) to be notified of future security updates.


    3. Check for firmware updates periodically through the Yadea mobile app or website, though none have been announced as of this publication.


    ### Organizational and Sector Recommendations


    Organizations operating Yadea T5 bicycles as part of shared mobility or corporate fleet programs should:


  • Implement physical locking procedures requiring secondary locks before unattended parking
  • Educate users about the wireless authentication weakness
  • Establish a replacement or upgrade strategy should Yadea fail to release a patch within a reasonable timeframe
  • Consider transitioning to competing e-bike models from manufacturers with stronger security records

    • ## What's Next?


    The onus now falls on Yadea to release a firmware update that implements proper cryptographic authentication, such as challenge-response protocols or rolling code mechanisms. Until such a patch is available, the vulnerability remains unpatched in all affected bikes. The company's lack of response to CISA coordination efforts raises concerns about whether a fix will be prioritized or released at all.


    Users should monitor Yadea's website and contact support channels for announcements. In the interim, physical locks remain the only reliable defense against this vulnerability.


    ## References


  • CISA Alert (Original Advisory): https://www.cisa.gov/news-events
  • CVE-2025-70994 Details: https://www.cve.org/CVERecord?id=CVE-2025-70994
  • Yadea Support Portal: https://yadea.com/contact-us
  • CISA ICS Security Best Practices: https://cisa.gov/ics
  • CWE-1390 Weak Authentication: https://cwe.mitre.org/data/definitions/1390.html

    • ---


    *This article is based on CISA's official vulnerability disclosure published April 23, 2026. No active exploitation of this vulnerability has been reported to CISA at the time of publication. This is not an advertisement for or against any manufacturer; the information is provided for security awareness and risk management purposes.*