diff --git a/api/core/helper/trace_id_helper.py b/api/core/helper/trace_id_helper.py
index e1ebd45e074..acf89706c93 100644
--- a/api/core/helper/trace_id_helper.py
+++ b/api/core/helper/trace_id_helper.py
@@ -22,7 +22,7 @@ def is_valid_trace_id(trace_id: str) -> bool:
 
     Requirements: 1-128 characters, only letters, numbers, '-', and '_'.
     """
-    return bool(re.match(r"^[a-zA-Z0-9\-_]{1,128}$", trace_id))
+    return bool(re.fullmatch(r"[a-zA-Z0-9\-_]{1,128}", trace_id))
 
 
 def get_external_trace_id(request: Any) -> str | None:
diff --git a/api/tests/unit_tests/core/helper/test_trace_id_helper.py b/api/tests/unit_tests/core/helper/test_trace_id_helper.py
index b5f6d6a11aa..ef03c7b5bf5 100644
--- a/api/tests/unit_tests/core/helper/test_trace_id_helper.py
+++ b/api/tests/unit_tests/core/helper/test_trace_id_helper.py
@@ -16,6 +16,24 @@ from core.helper.trace_id_helper import (
 )
 
 
+@pytest.mark.parametrize(
+    ("trace_id", "expected"),
+    [
+        ("abc", True),
+        ("a" * 128, True),
+        ("a" * 129, False),
+        # `$` also matches before a trailing newline, so "abc\n" used to slip
+        # through the character filter and the 128-character ceiling.
+        ("abc\n", False),
+        ("\nabc", False),
+        ("a" * 128 + "\n", False),
+        ("abc\r", False),
+    ],
+)
+def test_is_valid_trace_id_boundaries(trace_id: str, expected: bool) -> None:
+    assert is_valid_trace_id(trace_id) is expected
+
+
 def test_extract_trace_session_id_from_args_for_generator_extras():
     assert extract_trace_session_id_from_args({"trace_session_id": "session-1"}) == {
         "trace_session_id": "session-1",