CVE-2024-6959: Lollms Web UI DOS Vulnerability

CVE-2024-6959 Overview

CVE-2024-6959 is a Denial of Service (DoS) vulnerability in parisneo/lollms-webui version 9.8. The flaw resides in the audio file upload handler, which mishandles multipart form boundaries. An attacker can append a large number of characters to the end of a multipart boundary, forcing the server to continuously process each character and exhausting available resources. The absence of Cross-Site Request Forgery (CSRF) protection [CWE-352] permits remote exploitation through a victim's browser session. Successful exploitation renders the lollms-webui interface inaccessible, causing service disruption and extended downtime.

Critical Impact
Remote attackers can render lollms-webui inaccessible by submitting a crafted audio upload request, leading to resource exhaustion and prolonged service downtime.

Affected Products

lollms lollms_web_ui version 9.8
Component: lollms:lollms_web_ui
CPE: cpe:2.3:a:lollms:lollms_web_ui:9.8:*:*:*:*:*:*:*

Discovery Timeline

2024-10-13 - CVE-2024-6959 published to NVD
2024-11-03 - Last updated in NVD database

Technical Details for CVE-2024-6959

Vulnerability Analysis

The vulnerability affects the audio file upload endpoint in lollms-webui 9.8. The handler parses HTTP multipart/form-data requests and iterates over the boundary string used to separate form fields. When an attacker appends an excessive number of trailing characters to the multipart boundary, the server processes each character individually without imposing an upper bound. This unbounded iteration consumes CPU and memory until the application becomes unresponsive to legitimate requests.

The weakness is classified under [CWE-352] Cross-Site Request Forgery because the application lacks anti-CSRF tokens on state-changing endpoints. An attacker can host a malicious page that triggers the crafted upload from an authenticated user's browser. The combined effect transforms a server-side parsing flaw into a remotely exploitable DoS condition requiring only user interaction.

Root Cause

The root cause is improper input validation of the multipart boundary length in the audio upload route. The parser does not enforce a maximum boundary size and does not short-circuit on malformed boundary delimiters. Compounding this, the application omits CSRF protection on authenticated POST endpoints, enabling cross-origin abuse.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker crafts an HTML page or script that issues a POST request to the audio upload endpoint with a multipart boundary padded with thousands of trailing characters. When a logged-in user visits the attacker-controlled page, the browser submits the request with the user's session cookies. The lollms-webui server then enters a processing loop that exhausts available resources.

No synthetic exploitation code is included. See the Huntr Bounty Overview for technical details from the original report.

Detection Methods for CVE-2024-6959

Indicators of Compromise

Unusually long multipart boundary strings in HTTP POST requests to audio upload endpoints.
Sustained high CPU or memory consumption by the lollms-webui process following a single inbound request.
HTTP requests to the audio upload route originating from cross-origin Referer headers.
Application unresponsiveness or worker timeouts shortly after receiving multipart uploads.

Detection Strategies

Inspect web server access logs for POST requests with abnormally large Content-Type header values containing extended boundary strings.
Deploy a web application firewall (WAF) rule that flags multipart boundaries exceeding RFC 2046 practical limits (typically 70 characters).
Correlate sudden CPU spikes on the application host with concurrent inbound upload requests.

Monitoring Recommendations

Monitor process-level resource utilization for the lollms-webui service and alert on sustained saturation.
Track HTTP request latency and 5xx error rates for upload endpoints to identify availability degradation.
Log and review all multipart upload requests, retaining header metadata for forensic analysis.

How to Mitigate CVE-2024-6959

Immediate Actions Required

Restrict access to the lollms-webui audio upload endpoint to trusted networks until a vendor patch is applied.
Place the application behind a reverse proxy that enforces request size and header length limits.
Implement CSRF token validation on all state-changing endpoints to block cross-origin abuse.
Audit existing sessions and terminate any showing anomalous upload activity.

Patch Information

No vendor patch is listed in the available references at the time of NVD publication. Monitor the Huntr Bounty Overview and the upstream parisneo/lollms-webui repository for fix releases beyond version 9.8.

Workarounds

Configure an upstream proxy such as nginx to reject requests with Content-Type headers exceeding a sane length threshold.
Enforce strict multipart boundary length validation at the reverse proxy layer before requests reach the application.
Require SameSite=Strict cookies on authentication sessions to limit cross-site request forgery exposure.
Disable or gate the audio upload functionality through authentication middleware until patched.

bash

# Example nginx configuration to limit oversized multipart headers
http {
    client_header_buffer_size 1k;
    large_client_header_buffers 4 8k;
    client_max_body_size 10m;

    server {
        location /upload_audio {
            if ($http_content_type ~* "boundary=.{200,}") {
                return 413;
            }
            proxy_pass http://lollms_backend;
        }
    }
}