CVE-2026-41458: OwnTone Server DoS Vulnerability

CVE-2026-41458 Overview

OwnTone Server versions 28.4 through 29.0 contain a race condition vulnerability (CWE-362) in the DAAP login handler that allows unauthenticated attackers to crash the server. The vulnerability exists due to unsynchronized access to the global DAAP session list, which can be exploited by flooding the DAAP /login endpoint with concurrent requests to trigger a remote denial of service condition without requiring authentication.

Critical Impact

Unauthenticated remote attackers can crash OwnTone Server instances by exploiting the race condition in DAAP session handling, causing complete service disruption for media streaming services.

Affected Products

• OwnTone Server version 28.4
• OwnTone Server versions between 28.4 and 29.0
• OwnTone Server version 29.0

Discovery Timeline

• 2026-04-22 - CVE-2026-41458 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-41458

Vulnerability Analysis

This race condition vulnerability resides in the DAAP (Digital Audio Access Protocol) login handler within OwnTone Server. The root cause stems from improper synchronization when multiple concurrent requests attempt to access and modify the global DAAP session list simultaneously. When attackers flood the /login endpoint with parallel connection attempts, the unsynchronized access creates a Time-of-Check Time-of-Use (TOCTOU) scenario that leads to memory corruption or invalid state conditions, ultimately crashing the server process.

The attack can be executed remotely over the network without any authentication requirements, making it particularly dangerous for internet-exposed OwnTone Server instances. The vulnerability affects the availability of the service but does not impact confidentiality or integrity of the system.

Root Cause

The vulnerability originates from missing thread synchronization primitives around the global DAAP session list operations. When the login handler processes incoming authentication requests, it reads and writes to the shared session list without proper mutex locking or other concurrency controls. This allows multiple threads to corrupt the session list state when processing simultaneous login requests.

Attack Vector

The attack leverages the network-accessible DAAP protocol interface. An attacker can exploit this vulnerability by sending a high volume of concurrent HTTP requests to the DAAP /login endpoint. The lack of proper synchronization means that when these requests are processed in parallel, race conditions occur during session list manipulation. This can trigger crashes through corrupted data structures, double-free conditions, or null pointer dereferences when the server attempts to access invalidated session entries.

The attack requires no authentication and can be performed by any network-accessible attacker. The complexity lies in timing the concurrent requests to trigger the race condition, though flooding the endpoint with sufficient volume typically achieves reliable exploitation.

Detection Methods for CVE-2026-41458

Indicators of Compromise

• Unexpected OwnTone Server process crashes or restarts coinciding with high connection volumes
• Elevated error rates in OwnTone Server logs related to DAAP session handling
• Abnormal spikes in HTTP requests targeting the DAAP /login endpoint from single or multiple source IPs
• Core dump files indicating crashes within DAAP session management code paths

Detection Strategies

• Monitor OwnTone Server process stability and configure alerting for unexpected service restarts
• Implement rate limiting rules on network firewalls or reverse proxies for the DAAP /login endpoint
• Deploy network intrusion detection signatures to identify flooding patterns against DAAP services
• Review web server access logs for anomalous concurrent connection attempts to the /login path

Monitoring Recommendations

• Configure process monitoring to alert on OwnTone Server crashes with automatic restart tracking
• Implement connection rate monitoring at the network layer for DAAP service ports (typically TCP 3689)
• Enable verbose logging in OwnTone Server to capture session management events during incident investigation

How to Mitigate CVE-2026-41458

Immediate Actions Required

• Update OwnTone Server to a patched version that addresses the race condition in DAAP session handling
• Restrict network access to the DAAP service using firewall rules to trusted IP ranges only
• Implement rate limiting on the DAAP /login endpoint to prevent flood-based exploitation attempts
• Consider disabling DAAP protocol access temporarily if not required for operations

Patch Information

The OwnTone development team has addressed this vulnerability through commit dca94641a5ed66500822dd51281774794cdb6c22. The fix introduces proper synchronization mechanisms to protect the global DAAP session list from concurrent access issues. Organizations should update to the latest version of OwnTone Server that includes this patch. For additional context, refer to GitHub Pull Request #1980 and the security commit.

Workarounds

• Place OwnTone Server behind a reverse proxy with rate limiting configured for the DAAP endpoints
• Use firewall rules to restrict DAAP service access to internal networks or specific trusted hosts only
• Disable DAAP protocol support in OwnTone Server configuration if this functionality is not required
• Deploy a web application firewall (WAF) rule to detect and block high-frequency login request patterns

# Example: iptables rate limiting for DAAP service (port 3689)
iptables -A INPUT -p tcp --dport 3689 -m state --state NEW -m recent --set
iptables -A INPUT -p tcp --dport 3689 -m state --state NEW -m recent --update --seconds 60 --hitcount 20 -j DROP