diff --git a/app/integrated_app/openai_api.py b/app/integrated_app/openai_api.py
index dc8cf625..f1b7b3d9 100644
--- a/app/integrated_app/openai_api.py
+++ b/app/integrated_app/openai_api.py
@@ -163,6 +163,27 @@ def validate_model(cls, v: str) -> str:
 }
 
 
+# ---------------------------------------------------------------------------
+# 音色存在性判定
+# ---------------------------------------------------------------------------
+
+
+def _persona_wav_exists(name: str) -> bool:
+    """`name` 对应的音色 wav 是否真的在 PERSONA_DIR 之内。
+
+    旧写法是 `os.path.exists(os.path.join(PERSONA_DIR, f"{voice}.wav"))`，把请求体里的
+    `voice` 原样拼进路径：`../../..` 形式可以拿这条端点当**文件存在性探针**
+    （存在则继续合成、不存在才 400，响应差异即信息）。
+    这里只做目录归属判定，不做字符白名单——后者会误伤早期登记、名字里带空格或
+    全角字符的音色；遍历由 containment 挡住即可。
+    """
+    from .persona_manager import PERSONA_DIR
+
+    root = os.path.realpath(PERSONA_DIR)
+    candidate = os.path.realpath(os.path.join(root, f"{name}.wav"))
+    return candidate.startswith(root + os.sep) and os.path.isfile(candidate)
+
+
 # ---------------------------------------------------------------------------
 # 音频格式转换辅助
 # ---------------------------------------------------------------------------
@@ -809,11 +830,9 @@ async def create_speech(request: Request, body: SpeechRequest):
 
             engine_name = _MODEL_ENGINE_MAP.get(body.model, "voxcpm2")
             if engine_name == "voxcpm2" and body.voice and body.voice not in _VOICE_PERSONA_MAP:
-                import os as _os
+                from .persona_manager import get_persona_consent_state
 
-                from .persona_manager import PERSONA_DIR, get_persona_consent_state
-
-                if not _os.path.exists(_os.path.join(PERSONA_DIR, f"{body.voice}.wav")):
+                if not _persona_wav_exists(body.voice):
                     raise HTTPException(
                         status_code=400,
                         detail=(
@@ -982,11 +1001,9 @@ async def create_speech_batch(
                 )
             _engine_name = _MODEL_ENGINE_MAP.get(body.model, "voxcpm2")
             if _engine_name == "voxcpm2" and body.voice and body.voice not in _VOICE_PERSONA_MAP:
-                import os as _os
-
-                from .persona_manager import PERSONA_DIR, get_persona_consent_state
+                from .persona_manager import get_persona_consent_state
 
-                if not _os.path.exists(_os.path.join(PERSONA_DIR, f"{body.voice}.wav")):
+                if not _persona_wav_exists(body.voice):
                     raise HTTPException(
                         status_code=400,
                         detail=(
diff --git a/tests/test_openai_voice_path_probe.py b/tests/test_openai_voice_path_probe.py
new file mode 100644
index 00000000..96ebfd77
--- /dev/null
+++ b/tests/test_openai_voice_path_probe.py
@@ -0,0 +1,71 @@
+"""OpenAI 兼容端点的 `voice` 参数不得当文件存在性探针用。
+
+`openai_api._persona_wav_exists` 之前的写法是
+`os.path.exists(os.path.join(PERSONA_DIR, f"{voice}.wav"))`：请求体里的字符串被原样
+拼进路径，命中就继续合成、不命中才 400 —— 响应差异即泄露「该绝对路径是否存在」。
+这里锁住目录归属判定本身（端点级冒烟见 test_voice_clone_consent.py）。
+"""
+
+import sys
+from pathlib import Path
+
+import pytest
+
+_PROJECT_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(_PROJECT_ROOT / "app"))
+
+
+@pytest.fixture
+def persona_env(tmp_path, monkeypatch):
+    """PERSONA_DIR 指向临时目录，并在其**外面**放一个可被探针命中的 wav。"""
+    from integrated_app import openai_api, persona_manager
+
+    root = tmp_path / "personas"
+    root.mkdir()
+    outside = tmp_path / "secret_target"
+    outside.with_suffix(".wav").write_bytes(b"RIFF....WAVEfmt ")
+    inside = root / "alice"
+    inside.with_suffix(".wav").write_bytes(b"RIFF....WAVEfmt ")
+
+    monkeypatch.setattr(persona_manager, "PERSONA_DIR", str(root))
+    return openai_api, root, outside
+
+
+class TestPersonaWavExistsContainment:
+    def test_legitimate_persona_still_resolves(self, persona_env):
+        openai_api, _root, _outside = persona_env
+        assert openai_api._persona_wav_exists("alice") is True
+
+    def test_missing_persona_is_false(self, persona_env):
+        openai_api, _root, _outside = persona_env
+        assert openai_api._persona_wav_exists("nobody") is False
+
+    def test_relative_traversal_cannot_probe_outside(self, persona_env):
+        """旧写法在此返回 True（等于给攻击者一个存在性预言机）。"""
+        openai_api, root, outside = persona_env
+        import os
+
+        name = os.path.relpath(str(outside.with_suffix("")), str(root))
+        assert ".." in name, "夹具要真的越出 PERSONA_DIR"
+        assert openai_api._persona_wav_exists(name) is False
+
+    def test_absolute_name_cannot_probe_outside(self, persona_env):
+        """os.path.join(dir, 绝对名) 会整体丢弃 dir，旧写法直接命中任意路径。"""
+        openai_api, _root, outside = persona_env
+        assert openai_api._persona_wav_exists(str(outside.with_suffix(""))) is False
+
+    def test_sibling_prefix_not_treated_as_inside(self, tmp_path, monkeypatch):
+        """PERSONA_DIR=/x/personas 时 /x/personas_evil 不算其内部（前缀比对要带分隔符）。"""
+        from integrated_app import openai_api, persona_manager
+
+        root = tmp_path / "personas"
+        root.mkdir()
+        sibling = tmp_path / "personas_evil"
+        sibling.mkdir()
+        (sibling / "trap.wav").write_bytes(b"RIFF....WAVEfmt ")
+        monkeypatch.setattr(persona_manager, "PERSONA_DIR", str(root))
+
+        import os
+
+        name = os.path.relpath(str(sibling / "trap"), str(root))
+        assert openai_api._persona_wav_exists(name) is False