diff --git a/scripts/audit_c5_benchmark_evidence.py b/scripts/audit_c5_benchmark_evidence.py
index a1842a678..ee09185f7 100644
--- a/scripts/audit_c5_benchmark_evidence.py
+++ b/scripts/audit_c5_benchmark_evidence.py
@@ -22,6 +22,7 @@ from __future__ import annotations
 import argparse
 import errno
 import hashlib
+from html import escape as html_escape
 import json
 import os
 import posixpath
@@ -1413,15 +1414,47 @@ def audit(
 # Markdown summary
 # ---------------------------------------------------------------------------
 
+def _markdown_display_value(value: Any) -> str:
+    """Escape untrusted values without creating Markdown rows or HTML elements."""
+    raw = str(value).encode("utf-8", errors="backslashreplace").decode("utf-8")
+    safe = []
+    for char in raw:
+        if char == "\n":
+            safe.append(r"\n")
+        elif char == "\r":
+            safe.append(r"\r")
+        elif char == "\t":
+            safe.append(r"\t")
+        elif ord(char) < 32 or ord(char) == 127:
+            safe.append(f"\\x{ord(char):02x}")
+        elif char in ("\u0085", "\u2028", "\u2029"):
+            safe.append(f"\\u{ord(char):04x}")
+        else:
+            safe.append(char)
+    # HTML entities are decoded after Markdown table splitting, preserving columns.
+    return html_escape("".join(safe), quote=False).replace("|", "&#124;")
+
+
+def _markdown_code(value: Any) -> str:
+    return f"<code>{_markdown_display_value(value)}</code>"
+
+
+def _markdown_text(value: Any) -> str:
+    text = _markdown_display_value(value)
+    for char in ("`", "*", "_", "[", "]", "!"):
+        text = text.replace(char, f"&#{ord(char)};")
+    return text
+
+
 def _markdown_summary(result: dict[str, Any]) -> str:
     lines: list[str] = []
     lines.append("# Benchmark Evidence Audit Summary")
     lines.append("")
-    lines.append(f"- **Campaign**: `{result.get('campaign_id', 'unknown')}`")
+    lines.append(f"- **Campaign**: {_markdown_code(result.get('campaign_id', 'unknown'))}")
     lines.append(f"- **Audited at**: {result.get('audited_at', '')}")
     if result.get("timestamp_kind") == "deterministic_placeholder":
         lines.append("- **Timestamp note**: Fixed reproducibility placeholder (1970-01-01T00:00:00Z)")
-    lines.append(f"- **Root**: `{result.get('root', '')}`")
+    lines.append(f"- **Root**: {_markdown_code(result.get('root', ''))}")
     lines.append(f"- **Manifest valid**: {result.get('manifest_valid', False)}")
     lines.append("")
 
@@ -1440,7 +1473,7 @@ def _markdown_summary(result: dict[str, Any]) -> str:
         lines.append("## Errors")
         lines.append("")
         for e in errors:
-            lines.append(f"- {e}")
+            lines.append(f"- {_markdown_text(e)}")
         lines.append("")
 
     arts = result.get("artifacts", [])
@@ -1451,12 +1484,12 @@ def _markdown_summary(result: dict[str, Any]) -> str:
         lines.append("|---|---|---|---|---|")
         for a in arts:
             path = a.get("path", "")
-            display_path = str(path).encode("utf-8", errors="backslashreplace").decode("utf-8")
+            display_path = _markdown_code(path)
             atype = a.get("type") or ""
             status = a.get("status", "")
             present = "yes" if a.get("present") else ("no" if a.get("present") is False else "?")
             size = str(a.get("size_bytes")) if a.get("size_bytes") is not None else "-"
-            lines.append(f"| `{display_path}` | {atype} | **{status}** | {present} | {size} |")
+            lines.append(f"| {display_path} | {_markdown_text(atype)} | **{status}** | {present} | {size} |")
         lines.append("")
 
     prereqs = result.get("reproducibility_prerequisites", {})
@@ -1472,7 +1505,7 @@ def _markdown_summary(result: dict[str, Any]) -> str:
             es_status = det.get("expected_set_status", "UNKNOWN")
             comp = "yes" if det.get("prerequisite_complete") else "no"
             notes = det.get("notes") or ""
-            lines.append(f"| {k} | **{v}** | {integrity} | {es_status} | {comp} | {notes} |")
+            lines.append(f"| {k} | **{v}** | {integrity} | {es_status} | {comp} | {_markdown_text(notes)} |")
         lines.append("")
 
     return "\n".join(lines)
diff --git a/tests/test_audit_c5_benchmark_evidence.py b/tests/test_audit_c5_benchmark_evidence.py
index 0f970ce21..2f70ed117 100644
--- a/tests/test_audit_c5_benchmark_evidence.py
+++ b/tests/test_audit_c5_benchmark_evidence.py
@@ -2618,5 +2618,85 @@ class TestCliDiagnosticConfidentiality(unittest.TestCase):
                 self.assertNotIn("Traceback", stderr.getvalue())
 
 
+# ---------------------------------------------------------------------------
+# Markdown report integrity: untrusted values must remain within their cells.
+# ---------------------------------------------------------------------------
+
+class TestMarkdownReportIntegrity(unittest.TestCase):
+    def test_newline_and_pipe_in_missing_path_cannot_forge_verified_row(self):
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            bad_name = "not-found\n| apparent-success | result_record | **VERIFIED** | yes | 20 |"
+            manifest = root / "manifest.json"
+            manifest.write_text(json.dumps(_manifest([{
+                "path": bad_name, "type": "result_record"
+            }])))
+            result = auditor.audit(str(manifest), str(root), deterministic=True)
+            self.assertEqual(result["artifacts"][0]["status"], auditor.MISSING)
+            summary = auditor._markdown_summary(result)
+            artifact_section = summary.split("## Artifacts\n", 1)[1].split("## Reproducibility Prerequisites", 1)[0]
+            rows = [row for row in artifact_section.splitlines() if row.startswith("|")]
+            self.assertEqual(len(rows), 3)
+            self.assertNotIn("\n| apparent-success", summary)
+            self.assertIn("&#124; apparent-success", summary)
+            self.assertIn("**MISSING**", summary)
+
+    def test_code_delimiters_and_html_are_escaped(self):
+        value = "bad`</code><img src=x onerror=alert(1)>|name"
+        safe = auditor._markdown_code(value)
+        self.assertTrue(safe.startswith("<code>"))
+        self.assertTrue(safe.endswith("</code>"))
+        self.assertNotIn("<img", safe)
+        self.assertNotIn("</code><img", safe)
+        self.assertIn("&#124;", safe)
+        self.assertIn("&lt;", safe)
+
+    def test_campaign_and_notes_cannot_insert_headings_or_columns(self):
+        result = {
+            "campaign_id": "benchmark\n## Forged status",
+            "root": "/tmp/a|b",
+            "manifest_valid": True,
+            "totals": {status: 0 for status in auditor.ALL_STATUSES} | {"total": 0},
+            "reproducibility_prerequisites": {"raw_trajectories": auditor.INCOMPLETE},
+            "reproducibility_details": {"raw_trajectories": {"notes": "missing\n| VERIFIED | yes |"}},
+        }
+        summary = auditor._markdown_summary(result)
+        self.assertNotIn("\n## Forged status", summary)
+        prerequisite_section = summary.split("## Reproducibility Prerequisites", 1)[1]
+        self.assertNotIn("\n| VERIFIED", prerequisite_section)
+        self.assertIn("benchmark\\n## Forged status", summary)
+        self.assertIn("missing\\n&#124; VERIFIED", summary)
+
+    def test_cli_published_summary_does_not_forge_missing_artifact(self):
+        with tempfile.TemporaryDirectory() as td:
+            root = Path(td)
+            missing = "missing\n| forged | result_record | **VERIFIED** | yes | 99 |"
+            manifest = root / "manifest.json"
+            manifest.write_text(json.dumps(_manifest([{"path": missing, "type": "result_record"}])))
+            output = root / "audit.json"
+            summary = root / "audit.md"
+            code = auditor.main([str(manifest), str(root), "--output", str(output), "--summary", str(summary), "--deterministic"])
+            self.assertEqual(code, 1)
+            self.assertEqual(json.loads(output.read_text())["artifacts"][0]["status"], auditor.MISSING)
+            text = summary.read_text()
+            section = text.split("## Artifacts\n", 1)[1].split("## Reproducibility Prerequisites", 1)[0]
+            self.assertEqual(sum(line.startswith("|") for line in section.splitlines()), 3)
+            self.assertNotIn("\n| forged", text)
+            self.assertIn("**MISSING**", text)
+
+    def test_unicode_line_separators_do_not_create_new_rows(self):
+        for separator in (chr(0x85), chr(0x2028), chr(0x2029)):
+            safe = auditor._markdown_display_value("before" + separator + "after")
+            self.assertNotIn(separator, safe)
+            self.assertIn("after", safe)
+
+    def test_unicode_and_surrogates_remain_publishable(self):
+        text = auditor._markdown_code("café_測試_🚀" + chr(0xd800))
+        self.assertIn("café", text)
+        self.assertIn("測試", text)
+        self.assertIn("\\ud800", text)
+        text.encode("utf-8")
+
+
 if __name__ == "__main__":
     unittest.main()