CVE-2026-49127: MPD Stack Buffer Overflow in PCM Decoder (v0.24.11 Patch)

Technical summary

CVE-2026-49127 is a stack buffer overflow (CWE-193: Off-by-One Error) in the pcm_unpack_24be function within MPD's PCM decoder plugin. The vulnerability stems from an off-by-one condition in the unpack loop that attempts to write 1366 entries into a 1365-entry buffer. An attacker can trigger this by issuing two MPD commands that reference a malicious HTTP audio source. The overflow writes three attacker-controlled bytes from the HTTP response body four bytes past the array boundary, corrupting adjacent stack memory. Depending on what data overwrites the stack, this can lead to denial of service via daemon termination or potentially arbitrary code execution.

Business impact

Organizations running MPD as a network service face operational disruption risk. A successful exploit can crash the music playback service, affecting any systems or users depending on it. More critically, if code execution is achieved, attackers gain the privileges of the MPD process, potentially allowing lateral movement within networked audio infrastructure. The unauthenticated nature of the attack means no credentials or user interaction are needed—any MPD instance reachable over the network is exploitable.

Affected systems

Music Player Daemon (MPD) versions prior to 0.24.11 are vulnerable. Any deployment running an older version with network accessibility is at risk. This includes standalone audio servers, IoT devices running MPD, and containerized media services. Verify your MPD version and audit network exposure of any MPD instances in your environment.

Exploitability

The attack requires only network access to an MPD instance and no authentication. An attacker must craft and host a malicious audio file and issue two MPD commands pointing to it. The low complexity of the attack vector (CVSS AV:N/AC:L/PR:N/UI:N) and the straightforward nature of triggering the buffer overflow make this easily exploitable for a motivated attacker. The attacker controls the bytes written into the overflow, allowing some control over the outcome.

Remediation

Upgrade Music Player Daemon to version 0.24.11 or later. Verify the upgrade against the official MPD project advisory and release notes. After patching, validate that the service restarts cleanly and continues to function with existing configurations. For environments unable to patch immediately, restrict network access to MPD to trusted hosts only via firewall rules or network segmentation.

Patch guidance

Download and install MPD version 0.24.11 or newer from the official Music Player Daemon project repositories or your distribution's package manager. Follow standard deployment procedures for your environment: test the upgrade in a non-production instance first to ensure compatibility with existing configurations, then roll out to production systems during a scheduled maintenance window. Confirm the service starts without errors and that playback functionality remains intact post-patch.

Detection guidance

Monitor MPD logs for unusual playback commands or audio source requests, especially those referencing suspicious HTTP URLs. Network-based detection should focus on identifying connections to known malicious audio hosts or detection of multiple MPD commands in quick succession targeting external resources. Host-based monitoring should watch for unexpected MPD process crashes or restarts. Implement input validation logging in HTTP traffic to catch attempts to send oversized or malformed PCM data to MPD listeners.

Why prioritize this

A CVSS score of 8.6 (HIGH) reflects the combination of unauthenticated network accessibility, low attack complexity, and the potential for both denial of service and code execution. The absence of authentication requirements and the simplicity of crafting the exploit make this a priority for patching. Any internet-exposed or even intranet-accessible MPD instance should be treated as urgent.

Risk score, explained

The vulnerability scores HIGH (8.6) due to: (1) network-accessible attack surface with no authentication barrier (AV:N, PR:N); (2) low complexity to execute the attack (AC:L); (3) high impact on availability through denial of service (A:H); (4) moderate confidentiality and integrity impacts from potential code execution (C:L, I:L); and (5) unrestricted scope (S:U). The off-by-one error is relatively easy to trigger with minimal attacker effort, and the resulting memory corruption creates meaningful risk of both crash and code execution depending on stack layout and ASLR status.

Frequently asked questions