CVE-2024-8053: Open Webui PDF Endpoint DoS Vulnerability

CVE-2024-8053 Overview

CVE-2024-8053 affects Open WebUI version 0.3.10, where the api/v1/utils/pdf endpoint lacks authentication controls. Unauthenticated remote attackers can reach the PDF generation service directly over the network. The flaw is classified as Missing Authentication for Critical Function [CWE-306].

Attackers can send POST requests with oversized payloads to exhaust server resources and trigger a denial-of-service condition. Unauthorized users can also abuse the endpoint to generate PDFs at will, producing operational and financial impact on hosted instances. The issue was reported through the Huntr bug bounty program.

Critical Impact
An unauthenticated attacker can crash the Open WebUI service or consume compute resources by submitting large POST payloads to an unprotected PDF generation endpoint.

Affected Products

Open WebUI version 0.3.10
Component: openwebui:open_webui
CPE: cpe:2.3:a:openwebui:open_webui:0.3.10

Discovery Timeline

2025-03-20 - CVE-2024-8053 published to the National Vulnerability Database (NVD)
2025-03-27 - Last updated in NVD database

Technical Details for CVE-2024-8053

Vulnerability Analysis

Open WebUI exposes a PDF generation endpoint at api/v1/utils/pdf that processes POST requests without verifying caller identity. The endpoint is reachable over the network with no privileges or user interaction required. Because the service accepts arbitrary input sizes, attackers can submit large payloads that force the backend to allocate memory and CPU for PDF rendering.

Resource consumption scales with payload size, so repeated requests can degrade or crash the service. The vulnerability primarily impacts availability, with a secondary integrity impact from unauthorized PDF generation. The Exploit Prediction Scoring System (EPSS) places this issue at the 73rd percentile, indicating elevated likelihood of exploitation activity relative to other published CVEs.

Root Cause

The root cause is the absence of an authentication check on the api/v1/utils/pdf route handler. Functions that consume significant server resources must verify the requester before processing input. Open WebUI 0.3.10 ships this route without a session or token requirement, satisfying the conditions for [CWE-306] Missing Authentication for Critical Function.

Attack Vector

An attacker reaches the endpoint over HTTP without credentials. The attacker issues a POST request to api/v1/utils/pdf containing an excessively large body. The server attempts to parse the payload and generate a PDF, consuming memory and CPU. Repeated or concurrent requests exhaust available resources and deny service to legitimate users. The same endpoint can also be invoked at low volume to misuse the PDF generation capability for unauthorized output.

Technical details are documented in the Huntr Bounty Report.

Detection Methods for CVE-2024-8053

Indicators of Compromise

Unauthenticated POST requests to /api/v1/utils/pdf originating from unexpected source IPs
Spikes in request body size against the PDF endpoint, particularly payloads exceeding normal document sizes
Sustained high CPU or memory utilization on the Open WebUI host correlated with PDF endpoint traffic
HTTP 5xx errors or process restarts following bursts of PDF endpoint requests

Detection Strategies

Inspect web server and reverse proxy logs for POST requests to api/v1/utils/pdf lacking session cookies or authorization headers
Apply web application firewall (WAF) rules that flag requests to the endpoint when payload size exceeds a defined threshold
Correlate application crash events with prior request volume to the PDF route to confirm resource exhaustion

Monitoring Recommendations

Enable request rate and payload size metrics on the Open WebUI ingress for the api/v1/utils/pdf path
Alert on anomalous request rates from single source addresses to the PDF endpoint
Track process memory and CPU baselines for the Open WebUI service and alert on sustained deviations

How to Mitigate CVE-2024-8053

Immediate Actions Required

Upgrade Open WebUI to a version later than 0.3.10 that enforces authentication on the PDF endpoint
Restrict network access to the Open WebUI instance so that only authenticated users on trusted networks can reach the API
Place the application behind a reverse proxy that enforces authentication and request size limits

Patch Information

No vendor advisory URL is referenced in the NVD record. Review the Huntr Bounty Report and the Open WebUI project release notes for fixed versions and apply the latest stable release.

Workarounds

Block external access to the api/v1/utils/pdf route at the reverse proxy or WAF until a patched version is deployed
Enforce a maximum request body size on the proxy to prevent oversized payloads from reaching the application
Apply per-IP rate limiting on the PDF endpoint to reduce the impact of resource exhaustion attempts

bash

# Example NGINX configuration to restrict the PDF endpoint
location /api/v1/utils/pdf {
    # Limit request body size
    client_max_body_size 1m;

    # Rate limit per client IP
    limit_req zone=pdf_zone burst=5 nodelay;

    # Require authentication header at the proxy layer
    if ($http_authorization = "") {
        return 401;
    }

    proxy_pass http://open_webui_backend;
}