Vulnerability Analysis Report- CVE-2025-41702 -egOS WebGUI hard-coded JWT secret → authn/authz bypass

Vulnerability: egOS WebGUI hard-coded JWT secret → authn/authz bypass

CVE: CVE-2025-41702
Vendor / Product: Welotec egOS WebGUI on EG-series devices (EG400/EG500/EG503/EG602/EG802/EG804, etc.) certvde.com
Weakness: CWE-321 — Use of Hard-coded Cryptographic Key NVD
Severity: CVSS 9.8 (CRITICAL) — AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (CERT VDE CNA) NVD
Published: Aug 26, 2025 (NVD) NVD
Status: Fixes available in egOS v1.7.7 and v1.8.2; interim mitigations provided by CERT VDE. certvde.com

Summary

The JWT secret key used by egOS WebGUI is embedded in the backend and readable (exposed), allowing an unauthenticated remote attacker to forge valid HS256 tokens and bypass authentication/authorization to reach protected API endpoints. NVD certvde.com

Technical Details (concise)

Flaw: Hard-coded JWT secret present in WebGUI backend; secrecy is broken. NVD
Impact path: Attacker derives/reads the secret → signs HS256 JWTs → presents Authorization: Bearer token → gains privileged API access. NVD
Affected builds (examples): Multiple EG-series SKUs; affected egOS < v1.7.7 and v1.8.0 < v1.8.2 (see CERT VDE matrix). certvde.com

Risk & Impact

Confidentiality: Full read of device data, logs, and potentially stored credentials/tokens.
Integrity: Configuration changes, firmware uploads, credential manipulation via privileged endpoints.
Availability: Reboots or disruptive config pushes via authenticated APIs.
Exposure profile: Industrial/OT gateways deployed on public or partner networks; risk escalates if WebGUI is internet-exposed.

Mitigation & Remediation

Immediate actions (from vendor advisory):

Update egOS to v1.7.7 or v1.8.2 (fixed firmware). certvde.com
Until patched, disable WebGUI or restrict access strictly to trusted admin stations (management network/VPN). certvde.com

Hardening (CyberDudeBivash add-ons):

Remove any external exposure of WebGUI (no WAN/NAT).
Enforce mTLS/VPN for management; IP allow-lists at perimeter.
After upgrade, invalidate sessions and rotate any secrets that might have been stored on the device (API keys, admin passwords).
Inventory all Welotec EG devices; prioritize those reachable from untrusted networks.

Detection & Threat Hunting

Web logs: Look for abnormal spikes of Bearer JWT logins, especially without prior credential prompts.
Config audit: Unplanned changes to network, VPN, or user roles.
Firmware events: Unauthorized upload/upgrade actions.
Network intel: New management sessions from unknown IP ranges.

Timeline

Aug 26, 2025: NVD publishes CVE-2025-41702; CVSS 3.1 vector from CNA (CERT VDE). NVD
Aug 25–26, 2025 (CEST): CERT VDE advisory VDE-2025-076 with affected SKUs, mitigation, and fixed versions. certvde.com

Authoritative Sources

NVD CVE-2025-41702 — description, CVSS (CNA), publication date. NVD
CERT@VDE VDE-2025-076 — affected products matrix, fix versions 1.7.7 / 1.8.2, mitigation guidance. certvde.com
Aggregators (for quick overviews): SecAlerts, GHSA, PT dbugs. Security Alerts GitHub Dbugs

CyberDudeBivash Recommendation

Patch fast, lock management surfaces, and purge tokens. Treat this as a Priority-0 for any Welotec EG gateways reachable from partner or internet segments. Apply fixed egOS, restrict WebGUI, and review admin actions for the last 30–60 days.

Author: CyberDudeBivash
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