CVE-2026-59178

CRITICAL CVSS 9.8 PoC Available
Published: 2026-09-14
Modified: 2026-09-14
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AI Threat Summary

CVE-2026-59178 is a critical vulnerability with a CVSS score of 9.8 affecting the target software. Authentication can be bypassed allowing unauthenticated access. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

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.

Attack Chain
1
Reconnaissance

Attacker identifies authentication endpoint and tests for bypass conditions

2
Initial Access

Attacker exploits CVE-2026-59178 authentication flaw to gain unauthorized access without valid credentials

3
Discovery

Attacker enumerates accessible resources, users, and configurations

4
Collection

Attacker exfiltrates sensitive data accessible without proper authorization

MITRE ATT&CK Techniques
T1078 Valid Accounts
Initial Access

Authentication bypass grants attacker access as legitimate user

T1548 Abuse Elevation Control Mechanism
Privilege Escalation

Bypassed auth may grant elevated or admin-level permissions

Indicators of Compromise
Type Value Description
user_agent Mozilla/5.0 (compatible; exploit/1.0) Generic exploit scanner user agent pattern
url /api/vuln-endpoint?payload=<malicious> Exploit attempt against application endpoint — monitor access logs for anomalous params
Remediation
1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.
Quick Facts
CVE ID CVE-2026-59178
CVSS Score 9.8
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published 2026-09-14
Exploited No
CISA KEV No
PoC Available
References
External Resources
NVD Entry BleepingComputer The Hacker News