AutoBangumi Hard-Coded Default Credentials Authentication Bypass

Technical Analysis

The vulnerability stems from the add_default_user() function in AutoBangumi's database user module, which automatically creates a default admin account with hard-coded, publicly documented credentials on first run or whenever the users table is empty, with no forced password rotation or setup wizard enforcement. An unauthenticated attacker can simply POST these known credentials to the login endpoint to obtain a valid session/token and access all API functionality, including RSS ingestion rules and downloader (e.g., qBittorrent/Aria2) integration settings, which could be repurposed to trigger downloads of malicious payloads or exfiltrate configuration data. The CVSS 9.8 score reflects the low attack complexity, no privileges required, and full impact to confidentiality, integrity, and availability. Because AutoBangumi is often self-hosted alongside other automation and media-management tools, compromise of the host could expose adjacent credentials, API keys, or tokens; if any AI agent or automation pipeline is co-located on the same host or network segment and relies on shared secrets, downloader webhooks, or file-system access, an attacker pivoting through this flaw could intercept or manipulate agent-triggered file retrieval and configuration data, representing a credential and pipeline integrity risk to agent-driven media/download automation workflows.

Affected Systems

AutoBangumi versions prior to 3.2.8; self-hosted instances where the internal users database table is empty at startup (fresh installs, resets, or misconfigured deployments); deployments exposing the login/authentication endpoint to untrusted networks or the public internet.

Indicators of Compromise

• Default admin credentials seeded via add_default_user() (documented in AutoBangumi source/config, not unique per-deployment)
• Unauthenticated login attempts to /api/v1/auth or equivalent login endpoint using default admin username/password
• Unexpected changes to RSS feed subscriptions or downloader configuration without corresponding legitimate admin activity

Remediation Steps

1. 1

   Upgrade to AutoBangumi 3.2.8 or later

   Apply the patched release that removes or properly secures the hard-coded default credential seeding logic.

2. 2

   Force credential rotation on first run

   Immediately change the default administrator password after deployment, and verify no default account remains active with unmodified credentials.

3. 3

   Restrict network exposure

   Place AutoBangumi behind a VPN, reverse proxy with authentication, or firewall rules limiting access to trusted internal hosts only; do not expose the login endpoint directly to the internet.

4. 4

   Audit existing deployments

   Check logs for unauthorized logins using default credentials, review RSS and downloader configuration for unauthorized changes, and rotate any downstream credentials or API keys accessible from the compromised instance.

5. 5

   Segment automation hosts

   Isolate self-hosted media automation tools like AutoBangumi from hosts running AI agents or automation pipelines to limit lateral movement and credential exposure in case of compromise.