device-builder: Missing Authentication for Critical Functionality
CVE-2026-59178 is a critical-severity missing authentication for critical functionality vulnerability in device-builder from Esphome, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected device-builder versions: < 1.0.12. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.78% chance of exploitation within 30 days, higher than 56% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of device-builder you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Esphome | device-builder | < 1.0.12 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (github.com).
Official description
ESPHome Device Builder Dashboard is a dashboard for the ESPHome home management software. Prior to version 1.0.12, the dashboard reads its authentication credentials from `$ESPHOME_USERNAME` and `$ESPHOME_PASSWORD`. Earlier versions, and the legacy `esphome` dashboard, read the bare `$USERNAME` and `$PASSWORD` instead. When the env vars were renamed the bare names were dropped with no fallback, so an operator who had protected their dashboard with `USERNAME` / `PASSWORD` (as the older getting started guide documented) loses authentication on upgrade and the dashboard starts open to anyone who can reach its port. The issue is fixed in 1.0.12. The bare `$USERNAME` / `$PASSWORD` are accepted again as a deprecated fallback so previously protected instances stay protected across the upgrade without operator intervention, with a loud deprecation warning at startup directing operators to rename them to `$ESPHOME_USERNAME` / `$ESPHOME_PASSWORD`. The fallback is gated on `$PASSWORD` being set and is only adopted as a pair, so the OS provided `$USERNAME` is never read on its own and the original collision footgun stays closed. A lone bare `$PASSWORD` with no username still fails loud as a credential mismatch rather than starting unauthenticated. This restores compatibility rather than failing closed on the legacy names, because the priority is that an instance which was protected before the upgrade stays protected without the operator having to act; the deprecation warning plus a future removal handles the migration. Operators should migrate to the `$ESPHOME_*` names. The esphome container delivers the fix in the 2026.6.2 release, which bumps its pinned `esphome-device-builder` version to 1.0.12. Without upgrading, restore authentication immediately by setting the new env vars to the same values, on any affected version. Alternatively, do not expose the dashboard port to untrusted networks, and check the startup logs for the `WITHOUT AUTHENTICATION` banner to confirm whether a given instance is currently open.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Authentication for Critical Functionality
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
- When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data.
More Missing Authentication for Critical Functionality vulnerabilities (CWE-306)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in device-builder
- 8.8 High severity
Recent Missing Authentication for Critical Functionality vulnerabilities
- 8.2 High severity
- 7.4 High severity
- 8.2 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
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