TL;DR
Volkswagen has enforced a new security measure requiring client assertion, which blocks Home Assistant from accessing VW Connect services. This change affects users relying on smart home integrations for vehicle management.
Volkswagen has recently implemented a new security requirement that blocks Home Assistant from accessing VW Connect services by mandating client assertion, impacting users who rely on automation and smart home integrations for vehicle management.
According to reports from users and developers, Volkswagen now requires a client assertion during authentication, which Home Assistant’s VW Connect integration does not support. This change was identified following a failed login attempt where users received an error message indicating expired credentials and inability to re-login, despite the Android app and browser login still functioning correctly.
The issue was first noted in the context of the Home Assistant community, where users reported that their existing integrations ceased to work after the latest environment update. The change appears to be part of Volkswagen’s effort to enhance security, but specific technical details about the client assertion requirement have not been officially disclosed by VW.
Why It Matters
This change matters because it disrupts automated vehicle management for users relying on Home Assistant, a popular open-source smart home platform. The inability to authenticate with VW Connect affects functionalities such as remote start, vehicle status updates, and other automation features, potentially impacting user convenience and security.
It also raises questions about the compatibility of third-party integrations with Volkswagen’s evolving security policies, highlighting the challenges of balancing security and user flexibility in connected vehicle ecosystems.

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Background
Volkswagen has been gradually expanding its digital services through VW Connect and We Connect, offering features like remote vehicle control and status monitoring. As part of this ecosystem, Home Assistant’s integration allowed users to automate vehicle management tasks. Recent updates to VW Connect’s security protocols, however, seem to have introduced a client assertion requirement, which is not supported by the current Home Assistant implementation.
This issue emerged after VW’s latest app and portal updates, with affected users reporting login failures despite their credentials working via official apps and browsers. The exact technical nature of the client assertion requirement remains unconfirmed by Volkswagen, though it appears to be a move towards stronger security measures.
“Users are now unable to authenticate with VW Connect through Home Assistant after the latest update. The error points to a missing or invalid client assertion.”
— Home Assistant community member
“We are continuously updating our security protocols to protect user data and vehicle access.”
— Volkswagen spokesperson (unconfirmed)

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What Remains Unclear
It is not yet clear whether Volkswagen will provide a workaround or update the API to support client assertion, or if this change is permanent. Details about the technical implementation of the requirement remain undisclosed, and Volkswagen has not issued an official statement addressing the issue.

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What’s Next
Next steps include monitoring Volkswagen’s official channels for updates, potential developer workarounds, or API modifications. The Home Assistant community may attempt to develop support for client assertion if more technical details become available. Further updates from VW are expected in the coming weeks.

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Key Questions
What is client assertion and why does it block Home Assistant?
Client assertion is a security mechanism where the client must present a proof of identity during authentication. Volkswagen’s new requirement for client assertion is not supported by Home Assistant, causing login failures.
Will this issue be fixed soon?
It is currently unclear whether Volkswagen will update their API to support client assertion or if a workaround exists. The company has not issued an official statement yet.
Does this affect all VW Connect users?
Only users relying on third-party integrations like Home Assistant are affected. Users accessing VW Connect via official apps and portals continue to function normally.
Can I still control my vehicle through VW Connect directly?
Yes, official app and browser-based login still work, allowing vehicle control without issues.
What should I do if my Home Assistant integration stops working?
Monitor Volkswagen’s official updates and community discussions. Currently, no official fix is available, but future updates may restore compatibility.
Source: Hacker News