CVE-2025-29784: NamelessMC DoS Vulnerability via Search

CVE-2025-29784 Overview

CVE-2025-29784 is a denial-of-service vulnerability in NamelessMC, a website software package for Minecraft servers. The flaw exists in the forum search functionality of versions 2.1.4 and prior. The s parameter in GET requests for forum search lacks length validation. Attackers can submit excessively long search queries, triggering performance degradation and potential service outages. The vulnerability is network-exploitable, requires no authentication, and needs no user interaction. NamelessMC addressed the issue in version 2.2.0. The underlying weakness is classified as improper input validation [CWE-20].

Critical Impact

Unauthenticated remote attackers can degrade or disable NamelessMC forum availability by submitting oversized search queries.

Affected Products

• NamelessMC Nameless version 2.1.4
• All NamelessMC Nameless versions prior to 2.1.4
• Fixed in NamelessMC Nameless version 2.2.0

Discovery Timeline

• 2025-04-18 - CVE-2025-29784 published to NVD
• 2025-05-13 - Last updated in NVD database

Technical Details for CVE-2025-29784

Vulnerability Analysis

The vulnerability resides in the forum search handler of NamelessMC. The application accepts the s GET parameter as a search query without enforcing an upper bound on its length. When the server processes an oversized string, the search logic consumes excessive CPU and memory resources. Repeated or concurrent requests of this kind amplify the impact, exhausting server resources and rendering the forum unresponsive to legitimate users.

The issue affects confidentiality and integrity negligibly, but availability impact is high. Since NamelessMC is commonly deployed as a public-facing community portal for Minecraft servers, the search endpoint is reachable by any anonymous visitor. This exposure enables low-effort denial-of-service attacks against the underlying web host.

Root Cause

The root cause is missing input length validation on the s query parameter passed to the forum search routine. Without a sanity check on query size, the application performs expensive string matching and database operations on attacker-controlled input of arbitrary size. This is a classic improper input validation weakness [CWE-20].

Attack Vector

An unauthenticated remote attacker crafts an HTTP GET request to the forum search endpoint with an extremely long value in the s parameter. The server attempts to process the oversized query, leading to resource exhaustion. Repeated submission of such requests compounds the effect and can result in a full denial of service for the NamelessMC instance. No privileges or user interaction are required. See the GitHub Security Advisory GHSA-4hrq-rf96-c2jm for additional technical context.

Detection Methods for CVE-2025-29784

Indicators of Compromise

• HTTP GET requests to the forum search endpoint containing unusually large s parameter values
• Spikes in PHP-FPM or web worker CPU and memory consumption tied to forum search routes
• Slow response times or HTTP 5xx errors originating from the NamelessMC forum search handler
• Repeated search requests from a single source IP within short time intervals

Detection Strategies

• Inspect web server access logs for query strings where the s parameter exceeds a reasonable character threshold, such as 256 bytes
• Correlate web request anomalies with server-side resource metrics to identify availability impact
• Deploy WAF rules that flag or block GET requests with oversized query parameters targeting /forum/search paths

Monitoring Recommendations

• Monitor request rate and parameter length distributions on NamelessMC forum search endpoints
• Alert on sustained CPU utilization above baseline thresholds on the NamelessMC web tier
• Track database query duration for forum search operations and alert on outliers

How to Mitigate CVE-2025-29784

Immediate Actions Required

• Upgrade NamelessMC to version 2.2.0 or later, which contains the official fix
• Apply the upstream patch from NamelessMC commit f5341e5 if direct upgrade is not immediately possible
• Review web server and application logs for evidence of oversized search queries prior to patching

Patch Information

NamelessMC released the fix in version 2.2.0. The patch is delivered through commit f5341e56930a98978171e0a871d60f19ab30ebdd, which introduces length validation on the s search parameter. Release details are available in the NamelessMC v2.2.0 release notes.

Workarounds

• Configure a web application firewall to reject GET requests where the s parameter exceeds a defined maximum length
• Implement rate limiting on the forum search endpoint to throttle abusive clients
• Restrict forum search access to authenticated users where business requirements permit
• Place the NamelessMC instance behind a reverse proxy that enforces request size and query string length limits

# Example nginx mitigation: limit query string length and rate on forum search
location /forum/search {
    if ($query_string ~ "(^|&)s=.{257,}") { return 414; }
    limit_req zone=search_limit burst=5 nodelay;
    proxy_pass http://namelessmc_backend;
}