CVE-2026-68005: ACME mini_httpd DOS Vulnerability

CVE-2026-68005 Overview

CVE-2026-68005 is a denial-of-service vulnerability in ACME mini_httpd version 1.30 and earlier. The flaw resides in the HTTP request header parser within the handle_request() function. A remote, unauthenticated attacker can send a crafted HTTP request that triggers uncontrolled resource consumption [CWE-400], causing the server to become unresponsive. The vulnerability affects availability without impacting confidentiality or integrity.

Critical Impact
Remote, unauthenticated attackers can crash or hang the mini_httpd service by sending malformed HTTP request headers, denying legitimate users access to hosted web resources.

Affected Products

ACME mini_httpd 1.30
ACME mini_httpd versions prior to 1.30
Embedded devices and appliances bundling vulnerable mini_httpd builds

Discovery Timeline

2026-08-17 - CVE-2026-68005 published to NVD
2026-08-17 - Last updated in NVD database

Technical Details for CVE-2026-68005

Vulnerability Analysis

The defect lives in the request-parsing logic of mini_httpd, a lightweight HTTP server from ACME Labs. The handle_request() function processes incoming HTTP headers without enforcing sufficient limits on structure or resource usage. A remote attacker exploits this by transmitting specifically shaped HTTP headers over the network. The parser consumes excessive resources or enters a state that halts request handling. The service then stops responding to legitimate clients until the process is restarted.

mini_httpd is commonly embedded in routers, IP cameras, and other network appliances. In these deployments, restarting the process typically requires physical or administrative access, which extends the impact window.

Root Cause

The root cause is uncontrolled resource consumption [CWE-400] inside handle_request(). The header parser lacks proper bounds enforcement or input-shape validation. Malformed request headers trigger conditions that the parser cannot reject or short-circuit safely, resulting in service disruption.

Attack Vector

Exploitation requires only network reachability to the target HTTP service. No authentication, no user interaction, and no prior foothold are needed. Attackers deliver the malicious HTTP request directly to the listening TCP port, typically 80 or 443. The impact is limited to availability; the vulnerability does not permit code execution or data disclosure.

The vulnerability manifests during HTTP header parsing inside handle_request(). See the GitHub CVE-2026-68005 Details writeup for reproduction details and the ACME mini_httpd project page for source references.

Detection Methods for CVE-2026-68005

Indicators of Compromise

Sudden unresponsiveness of mini_httpd processes with elevated CPU or memory utilization on the host.
Repeated inbound HTTP requests with malformed, oversized, or structurally invalid header fields from a single or small set of source IPs.
Web server crash or restart events without corresponding application error patterns in access logs.

Detection Strategies

Inspect HTTP traffic for anomalous header structures, excessive header counts, or oversized header values targeting embedded web services.
Monitor process health of mini_httpd for hangs, restarts, or memory pressure correlated with inbound HTTP bursts.
Correlate network telemetry with endpoint process telemetry to identify DoS attempts against exposed lightweight web servers.

Monitoring Recommendations

Enable rate-based alerting on the perimeter or reverse proxy for repeated malformed HTTP requests to mini_httpd endpoints.
Track availability metrics and TCP connection failures for hosts running mini_httpd.
Log and review reverse-proxy or WAF rejections that indicate probing of header parsers.

How to Mitigate CVE-2026-68005

Immediate Actions Required

Restrict network exposure of mini_httpd to trusted management networks using firewall rules or ACLs.
Place vulnerable instances behind a reverse proxy or WAF that enforces strict HTTP header validation.
Enumerate embedded devices and appliances that ship mini_httpd and prioritize those reachable from untrusted networks.

Patch Information

At the time of publication, no fixed version of ACME mini_httpd is referenced in the NVD entry. Monitor the ACME mini_httpd project page for updated releases and apply upstream fixes as they become available. For embedded deployments, consult the device vendor for firmware updates that incorporate a patched build.

Workarounds

Deploy a reverse proxy such as nginx or haproxy in front of mini_httpd to normalize and validate HTTP headers before they reach the vulnerable parser.
Enforce request size and header count limits at the network edge, dropping requests with abnormal structures.
Isolate affected devices on segmented VLANs and block direct HTTP access from untrusted networks until a patched build is available.

bash

# Example: front mini_httpd with nginx to filter malformed headers
# /etc/nginx/conf.d/mini_httpd_proxy.conf
server {
    listen 80;
    server_name _;

    large_client_header_buffers 4 8k;
    client_header_buffer_size 1k;
    client_max_body_size 1m;

    location / {
        proxy_pass http://127.0.0.1:8080;  # mini_httpd bound to localhost
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}