GHSA-52vm-mxx8-f227
HIGHPhantom: Arbitrary file write and decode-bomb DoS via unconfined MCP tool paths
Blast Radius
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Description
Impact
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.
Patches
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_EXCLoutput creation in reference matching and symlink-TOCTOU hardening on confined input reads.
Workarounds
Set PHANTOM_OUTPUT_DIR (and optionally PHANTOM_AUDIO_DIR) to dedicated directories before starting the server.
Credit
Found during an internal security audit.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | phantom-audio | all versions | 1.3.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phantom-audio. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update phantom-audio to 1.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-52vm-mxx8-f227 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-52vm-mxx8-f227 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-52vm-mxx8-f227. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-52vm-mxx8-f227 in your dependencies?
O3 detects GHSA-52vm-mxx8-f227 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.