CVE-2026-12620: GridTime 3000 Information Disclosure Flaw

CVE-2026-12620 Overview

CVE-2026-12620 affects the Microchip GridTime 3000 GNSS Time Server. The device leaks authentication access tokens through URL query parameters on certain HTTP endpoints. Tokens placed in URLs are stored in server access logs, browser history, proxy caches, and referrer headers. Attackers who obtain these logs or intercept referrer data can reuse the tokens to impersonate authenticated users.

The issue affects GridTime 3000 firmware versions 1.0r0.03 through 1.1r0.0. The flaw is categorized under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.

Critical Impact
Authenticated session tokens transmitted in URL parameters can be harvested from logs, caches, and referrer headers, enabling session replay against precision time infrastructure.

Affected Products

Microchip GridTime 3000 GNSS Time Server firmware 1.0r0.03
Microchip GridTime 3000 GNSS Time Server firmware versions between 1.0r0.03 and 1.1r0.0
Microchip GridTime 3000 GNSS Time Server firmware 1.1r0.0

Discovery Timeline

2026-06-19 - CVE-2026-12620 published to the National Vulnerability Database
2026-06-22 - Last updated in NVD database

Technical Details for CVE-2026-12620

Vulnerability Analysis

The GridTime 3000 web management interface transmits authentication tokens as URL query string parameters on selected endpoints. URL parameters are recorded in multiple locations outside the secure session boundary. Web server access logs capture the full request line, including the token value. Browser history, bookmark stores, and proxy server logs retain the same data. Outbound HTTP requests triggered from authenticated pages include the originating URL in the Referer header, exposing tokens to third-party hosts.

An attacker with read access to any of these artifacts can extract a valid token and replay it against the device. Because GNSS time servers underpin synchronization for power grid telemetry, financial transaction logging, and industrial control systems, unauthorized administrative access carries operational consequences beyond the device itself.

Exploitation requires that an authenticated user interact with an affected endpoint. The CVSS 4.0 vector indicates network attack vector with high privileges required and user interaction, resulting in low confidentiality impact against the vulnerable component.

Root Cause

The root cause is an insecure session handling design that passes bearer tokens through GET request query strings rather than Authorization headers, POST bodies, or HttpOnly cookies. Standards such as RFC 6750 explicitly warn against the URI query parameter method for exactly this exposure class.

Attack Vector

An attacker obtains a token by reading device or upstream proxy access logs, recovering browser history from an administrative workstation, or inspecting third-party referrer logs reached from an authenticated session. The captured token is then submitted to the GridTime 3000 management API to perform actions as the original user.

No verified proof-of-concept code is published for this issue. Refer to the Microchip Security Vulnerability Reporting page for vendor technical details.

Detection Methods for CVE-2026-12620

Indicators of Compromise

HTTP requests to the GridTime 3000 management interface containing token values inside query string parameters such as ?access_token=, ?token=, or ?session=.
Outbound HTTP requests from the device or administrative workstations carrying Referer headers that include token query parameters.
Repeated authenticated API calls from source IP addresses that have not previously interacted with the device administrative plane.

Detection Strategies

Parse web server and reverse proxy access logs for query strings that contain credential-like parameters and correlate them with the GridTime 3000 management URL.
Inspect SIEM-ingested HTTP telemetry for requests where the same token value appears across multiple distinct client IP addresses, indicating replay.
Review browser history exports and endpoint forensic snapshots from administrative workstations for URLs containing token parameters.

Monitoring Recommendations

Enable verbose authentication and access logging on the GridTime 3000 and forward events to a centralized log platform.
Alert on administrative actions originating from unexpected source networks or outside maintenance windows.
Monitor egress traffic from administrative workstations for Referer headers leaking GridTime URLs to external hosts.

How to Mitigate CVE-2026-12620

Immediate Actions Required

Restrict network access to the GridTime 3000 management interface to a dedicated management VLAN with explicit allow-listed administrative hosts.
Rotate all administrative credentials and invalidate active sessions on affected devices to revoke any tokens that may already be exposed in logs.
Sanitize or purge historical web server, proxy, and SIEM logs that contain captured token values, applying retention controls to limit future exposure.

Patch Information

Consult the Microchip Security Vulnerability Reporting page for GridTime 3000 for the current vendor advisory and firmware update guidance. Upgrade beyond firmware 1.1r0.0 when a fixed release becomes available.

Workarounds

Place the GridTime 3000 behind a reverse proxy configured to strip token query parameters from logs and rewrite them into Authorization headers where feasible.
Disable browser-based administration from shared workstations and require administrators to use isolated jump hosts whose history and cache are wiped between sessions.
Block outbound internet access from administrative workstations to prevent token leakage through Referer headers to external services.

bash

# Example nginx configuration to redact token parameters from access logs
log_format gridtime_safe '$remote_addr - $remote_user [$time_local] '
                        '"$request_method $uri $server_protocol" '
                        '$status $body_bytes_sent '
                        '"$http_user_agent"';

server {
    listen 443 ssl;
    server_name gridtime.internal.example;

    access_log /var/log/nginx/gridtime.log gridtime_safe;

    # Drop Referer on outbound links from the management UI
    add_header Referrer-Policy "no-referrer" always;

    location / {
        proxy_pass https://gridtime-backend;
        proxy_set_header Authorization $arg_access_token;
    }
}