GHSA-52VM-MXX8-F227

Phantom: Arbitrary file write and decode-bomb DoS via unconfined MCP tool paths

Workarounds

Set PHANTOM_OUTPUT_DIR (and optionally PHANTOM_AUDIO_DIR) to dedicated directories before starting the server.

Credit

Found during an internal security audit.

In Phantom <= 1.3.0, when PHANTOM_OUTPUT_DIR was unset (the default), the MCP tools accepted arbitrary absolute output paths with no confinement. Anything able to send tool calls (e.g. an AI agent driving the MCP interface) could write or overwrite arbitrary files the process user can write, including shell startup files (~/.zshrc) or a Reaper __startup.lua, which is effectively local code execution on a developer workstation.

Separately, the stem-separation and render paths decoded input audio with no size/duration cap (the analysis path was already guarded). A small, highly compressed FLAC/OGG could expand to multi-gigabyte PCM, causing memory-exhaustion DoS, and widened exposure to decoder bugs including libsndfile CVE-2026-37555.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

GHSA-52VM-MXX8-F227 has a CVSS score of 7.7 (High). The vector is requires local access, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.3.1); upgrading removes the vulnerable code path.

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Fixed in 1.3.1:

• File writes are always confined to PHANTOM_OUTPUT_DIR (default ~/.phantom/output); symlinks resolved and re-verified on the final path.
• Decode/duration/size guards mirrored onto the separation and render paths (plus ffmpeg -max_alloc/-t/-fs).
• Atomic O_CREAT|O_EXCL output creation in reference matching and symlink-TOCTOU hardening on confined input reads.

1. What is GHSA-52VM-MXX8-F227? GHSA-52VM-MXX8-F227 is a high-severity path traversal vulnerability in phantom-audio (pip), affecting versions <= 1.3.0. It is fixed in 1.3.1. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is GHSA-52VM-MXX8-F227? GHSA-52VM-MXX8-F227 has a CVSS score of 7.7 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of phantom-audio are affected by GHSA-52VM-MXX8-F227? phantom-audio (pip) versions <= 1.3.0 is affected.
4. Is there a fix for GHSA-52VM-MXX8-F227? Yes. GHSA-52VM-MXX8-F227 is fixed in 1.3.1. Upgrade to this version or later.
5. Is GHSA-52VM-MXX8-F227 exploitable, and should I be worried? Whether GHSA-52VM-MXX8-F227 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-52VM-MXX8-F227 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-52VM-MXX8-F227? Upgrade phantom-audio to 1.3.1 or later.