CVE-2026-25505: Bambuddy Auth Bypass Vulnerability

CVE-2026-25505 Overview

CVE-2026-25505 is an Authentication Bypass vulnerability affecting Bambuddy, a self-hosted print archive and management system designed for Bambu Lab 3D printers. Prior to version 0.1.7, the application contains a hardcoded secret key used for signing JSON Web Tokens (JWTs) that was checked into the source code repository. Additionally, many API routes fail to implement proper authentication checks, allowing unauthenticated access to sensitive functionality.

Critical Impact
Attackers can forge valid JWT tokens using the publicly exposed secret key, gaining unauthorized access to over 200 API endpoints that lack authentication enforcement. This enables complete compromise of the print management system, including control of connected 3D printers.

Affected Products

Bambuddy versions prior to 0.1.7
Self-hosted Bambuddy installations using default configurations
Deployments with network-accessible API endpoints

Discovery Timeline

February 4, 2026 - CVE-2026-25505 published to NVD
February 5, 2026 - Last updated in NVD database

Technical Details for CVE-2026-25505

Vulnerability Analysis

This vulnerability stems from two critical security flaws that combine to create a severe authentication bypass condition. First, the application uses a hardcoded JWT signing secret that was committed to the public source code repository. This secret key, located in the authentication module at backend/app/core/auth.py, can be extracted by any attacker with access to the repository, allowing them to forge arbitrary JWT tokens that the application will accept as valid.

Second, over 200 API endpoints in the application lack proper authentication enforcement. These routes can be accessed without any authentication tokens, exposing sensitive functionality to unauthenticated users. The combination of these flaws means that even if an endpoint does check for a JWT, an attacker can forge a valid token using the publicly known secret.

Root Cause

The root cause is classified under CWE-306 (Missing Authentication for Critical Function). The developers failed to implement a secure key management practice by hardcoding the JWT secret directly in the source code. Additionally, the API routes were designed without authentication middleware, leaving critical functions exposed. This architectural oversight affects the entire backend API surface area.

Attack Vector

The vulnerability is exploitable over the network with no prerequisites. An attacker can:

Clone or access the public Bambuddy repository to extract the hardcoded JWT secret
Generate forged JWT tokens with arbitrary user claims and elevated privileges
Access any of the 200+ unauthenticated API endpoints directly
Control connected Bambu Lab 3D printers, access print archives, and manipulate system configurations

python

# Security patch in backend/app/api/routes/ams_history.py
# Source: https://github.com/maziggy/bambuddy/commit/a82f9278d2d587b7042a0858aab79fd8b6e3add9

 from sqlalchemy import and_, func, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from backend.app.core.auth import RequirePermissionIfAuthEnabled
 from backend.app.core.database import get_db
+from backend.app.core.permissions import Permission
 from backend.app.models.ams_history import AMSSensorHistory
+from backend.app.models.user import User
 
 router = APIRouter(prefix="/ams-history", tags=["ams-history"])

The patch demonstrates the addition of RequirePermissionIfAuthEnabled authentication middleware and permission-based access control to previously unprotected API routes.

Detection Methods for CVE-2026-25505

Indicators of Compromise

Unexpected API requests to Bambuddy endpoints from external IP addresses
JWT tokens in application logs containing unusual or fabricated user claims
Authentication events with tokens signed using the known compromised secret
Unauthorized modifications to print archives, printer configurations, or user accounts

Detection Strategies

Monitor web server access logs for unauthenticated requests to sensitive API endpoints under /ams-history, /api-keys, and other protected routes
Implement JWT validation logging to detect tokens with unexpected payload contents or signing anomalies
Review application logs for authentication bypass attempts or mass enumeration of API endpoints
Deploy network-based intrusion detection rules to identify exploitation patterns targeting Bambuddy installations

Monitoring Recommendations

Enable verbose logging on all Bambuddy API routes to capture request metadata and authentication status
Configure alerts for API access patterns indicative of reconnaissance or exploitation activity
Establish baseline metrics for normal API usage to identify anomalous spikes in request volume
Monitor for unauthorized printer control commands or configuration changes

How to Mitigate CVE-2026-25505

Immediate Actions Required

Upgrade Bambuddy to version 0.1.7 or later immediately
Regenerate all JWT secrets and ensure they are stored securely outside of version control
Invalidate all existing JWT tokens and force re-authentication for all users
Review access logs for evidence of unauthorized access prior to patching
Restrict network access to Bambuddy instances using firewall rules or VPN requirements

Patch Information

The vulnerability has been patched in Bambuddy version 0.1.7. The fix adds the RequirePermissionIfAuthEnabled authentication middleware to over 200 API endpoints and implements proper permission-based access control. The security patch can be reviewed in the GitHub Commit Reference. Additional details are available in the GitHub Security Advisory.

Workarounds

Place Bambuddy behind a reverse proxy with authentication requirements until patching is possible
Implement network segmentation to restrict access to trusted internal networks only
Disable public-facing access to Bambuddy instances until the upgrade is completed
Monitor and rate-limit API requests to reduce the impact of potential exploitation

bash

# Configuration example - Restrict access using firewall rules
# Allow only trusted internal network access to Bambuddy
sudo ufw allow from 192.168.1.0/24 to any port 8080 proto tcp
sudo ufw deny from any to any port 8080 proto tcp
sudo ufw reload