diff --git a/scripts/security_patch_applier.py b/scripts/security_patch_applier.py
new file mode 100644
index 0000000..2126020
--- /dev/null
+++ b/scripts/security_patch_applier.py
@@ -0,0 +1,249 @@
+#!/usr/bin/env python3
+"""
+Security Patch Applier — 5.7
+
+Detects outdated dependencies, creates a branch, updates requirements,
+runs tests, and opens a PR via Gitea API.
+
+Usage:
+    python3 scripts/security_patch_applier.py
+    python3 scripts/security_patch_applier.py --dry-run  # Preview changes without PR
+    python3 scripts/security_patch_applier.py --pkg pytest  # Target specific package
+
+Acceptance:
+  - Detects security update   (checks pip list --outdated)
+  - Creates branch            (git checkout -b step35/security/patch-<pkg>-<ver>)
+  - Updates dependency        (modifies requirements.txt)
+  - Runs tests                (python3 -m pytest)
+  - Opens PR                  (Gitea API, Closes #<issue>)
+"""
+
+import argparse
+import json
+import subprocess
+import sys
+import urllib.request
+from pathlib import Path
+from typing import Optional, Tuple
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+REQUIREMENTS_PATH = REPO_ROOT / "requirements.txt"
+GITEA_TOKEN_PATH = Path.home() / ".config" / "gitea" / "token"
+GITEA_API_BASE = "https://forge.alexanderwhitestone.com/api/v1"
+GITEA_OWNER = "Timmy_Foundation"
+GITEA_REPO = "compounding-intelligence"
+
+
+def run_cmd(cmd: list[str], check: bool = True, capture: bool = True) -> subprocess.CompletedProcess:
+    """Run a subprocess, return result."""
+    result = subprocess.run(
+        cmd,
+        cwd=REPO_ROOT,
+        capture_output=capture,
+        text=True
+    )
+    if check and result.returncode != 0:
+        print(f"ERROR: {' '.join(cmd)} failed with code {result.returncode}")
+        print(result.stderr)
+        sys.exit(result.returncode)
+    return result
+
+
+def get_outdated_packages() -> list[dict]:
+    """Return list of outdated packages from pip list --outdated."""
+    result = run_cmd([sys.executable, "-m", "pip", "list", "--outdated", "--format=json"])
+    outdated = json.loads(result.stdout)
+    return outdated
+
+
+def parse_requirements() -> list[Tuple[str, str]]:
+    """Parse requirements.txt into list of (raw_line, package_name_lower)."""
+    if not REQUIREMENTS_PATH.exists():
+        print(f"ERROR: requirements.txt not found at {REQUIREMENTS_PATH}")
+        sys.exit(1)
+
+    lines = REQUIREMENTS_PATH.read_text().splitlines()
+    parsed = []
+    for line in lines:
+        stripped = line.strip()
+        if not stripped or stripped.startswith('#'):
+            continue
+        # Extract package name before any version specifier
+        pkg_name = stripped.split()[0].split('>=')[0].split('==')[0].split('~=')[0].split('<')[0].split('>')[0].lower()
+        parsed.append((stripped, pkg_name))
+    return parsed
+
+
+def update_requirements(package: str, new_version: str) -> bool:
+    """Update the version specifier for package in requirements.txt. Return True if changed."""
+    lines = REQUIREMENTS_PATH.read_text().splitlines()
+    updated = False
+    new_lines = []
+    for line in lines:
+        stripped = line.strip()
+        if not stripped or stripped.startswith('#'):
+            new_lines.append(line)
+            continue
+        # Check if this line contains the target package
+        pkg_name = stripped.split()[0].split('>=')[0].split('==')[0].split('~=')[0].split('<')[0].split('>')[0].lower()
+        if pkg_name == package.lower():
+            # Replace version spec with new version using >=
+            old_line = line
+            # Preserve original package name case
+            original_pkg = stripped.split()[0]
+            new_line = f"{original_pkg}>={new_version}"
+            # Preserve any trailing comment
+            if '#' in line:
+                comment = line.split('#', 1)[1]
+                new_line += f"  #{comment}"
+            new_lines.append(new_line)
+            updated = True
+        else:
+            new_lines.append(line)
+    if updated:
+        REQUIREMENTS_PATH.write_text('\n'.join(new_lines) + '\n')
+        return True
+    return False
+
+
+def create_branch(branch_name: str) -> bool:
+    """Create and checkout a new branch."""
+    # Check if branch already exists
+    result = run_cmd(["git", "branch", "--list", branch_name], check=False)
+    if result.stdout.strip():
+        print(f"Branch {branch_name} already exists.")
+        return False
+    result = run_cmd(["git", "checkout", "-b", branch_name])
+    return True
+
+
+def run_tests() -> bool:
+    """Run pytest. Return True if all pass."""
+    print("\nRunning tests...")
+    result = run_cmd([sys.executable, "-m", "pytest", "tests/test_ci_config.py", "scripts/test_*.py", "-v"], check=False)
+    return result.returncode == 0
+
+
+def get_gitea_token() -> str:
+    """Read Gitea token from file."""
+    if not GITEA_TOKEN_PATH.exists():
+        print(f"ERROR: Gitea token not found at {GITEA_TOKEN_PATH}")
+        sys.exit(1)
+    return GITEA_TOKEN_PATH.read_text().strip()
+
+
+def create_gitea_pr(title: str, body: str, head: str, base: str = "main") -> int:
+    """Create a pull request via Gitea API. Return PR number."""
+    token = get_gitea_token()
+    payload = json.dumps({
+        "title": title,
+        "body": body,
+        "head": head,
+        "base": base
+    }).encode('utf-8')
+    url = f"{GITEA_API_BASE}/repos/{GITEA_OWNER}/{GITEA_REPO}/pulls"
+    req = urllib.request.Request(
+        url,
+        data=payload,
+        headers={
+            "Authorization": f"token {token}",
+            "Content-Type": "application/json",
+            "Accept": "application/json"
+        },
+        method="POST"
+    )
+    try:
+        with urllib.request.urlopen(req, timeout=15) as resp:
+            data = json.loads(resp.read())
+            return data["number"]
+    except urllib.error.HTTPError as e:
+        body = e.read().decode('utf-8')
+        print(f"ERROR: Gitea API returned {e.code}: {body}")
+        sys.exit(1)
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Security Patch Applier — detect, fix, PR")
+    parser.add_argument("--dry-run", action="store_true", help="Preview without modifying files or opening PR")
+    parser.add_argument("--pkg", help="Target specific package (skip detection)")
+    parser.add_argument("--version", help="Specific version to update to (requires --pkg)")
+    args = parser.parse_args()
+
+    # Step 1: Detect outdated packages (security patches)
+    if args.pkg:
+        # Manual mode
+        if not args.version:
+            print("ERROR: --version required when using --pkg")
+            sys.exit(1)
+        outdated = [{"name": args.pkg, "latest_version": args.version, "version": "unknown"}]
+    else:
+        print("Checking for outdated dependencies...")
+        outdated = get_outdated_packages()
+        if not outdated:
+            print("No outdated packages found. System is up-to-date.")
+            sys.exit(0)
+        print(f"Found {len(outdated)} outdated package(s):")
+        for pkg in outdated:
+            print(f"  {pkg['name']}: {pkg.get('version', 'unknown')} → {pkg['latest_version']}")
+
+    # Pick first package for smallest fix (can loop for multiple)
+    target = outdated[0]
+    pkg_name = target["name"]
+    latest_ver = target["latest_version"]
+    current_ver = target.get("version", "unknown")
+
+    print(f"\nProcessing security patch for: {pkg_name} ({current_ver} → {latest_ver})")
+
+    if args.dry_run:
+        print("[DRY-RUN] Would create branch, update requirements, run tests, and open PR.")
+        sys.exit(0)
+
+    # Step 2: Create branch
+    branch_name = f"step35/security/patch-{pkg_name}-{latest_ver}"
+    print(f"\nCreating branch: {branch_name}")
+    if not create_branch(branch_name):
+        print(f"Branch {branch_name} already exists or could not be created.")
+        # Continue anyway? Let's exit
+        sys.exit(1)
+
+    # Step 3: Update requirements.txt
+    print(f"Updating {REQUIREMENTS_PATH} to {pkg_name}>={latest_ver}")
+    if not update_requirements(pkg_name, latest_ver):
+        print(f"ERROR: Failed to update {pkg_name} in requirements.txt")
+        sys.exit(1)
+    print(f"Updated requirements.txt")
+
+    # Step 4: Run tests
+    if not run_tests():
+        print("ERROR: Tests failed. Aborting PR creation.")
+        # Could revert branch? For minimal fix, just exit with error
+        sys.exit(1)
+    print("Tests passed.")
+
+    # Step 5: Commit changes
+    commit_msg = f"security: update {pkg_name} to {latest_ver}\n\nDetected outdated dependency via pip list --outdated.\n\nRefs: #113"
+    run_cmd(["git", "add", "requirements.txt"])
+    run_cmd(["git", "commit", "-m", commit_msg])
+
+    # Step 6: Push branch
+    print(f"\nPushing branch {branch_name}...")
+    result = run_cmd(["git", "push", "origin", branch_name], check=False)
+    if result.returncode != 0:
+        print(f"ERROR: Push failed: {result.stderr}")
+        sys.exit(1)
+
+    # Step 7: Open PR
+    pr_title = f"security: update {pkg_name} to {latest_ver}"
+    pr_body = (
+        f"Automated security patch for **{pkg_name}**.\n\n"
+        f"**Current version:** {current_ver}\n"
+        f"**Latest version:** {latest_ver}\n\n"
+        f"Detected by `pip list --outdated`. Tests passed locally.\n\n"
+        f"Closes #113"
+    )
+    pr_num = create_gitea_pr(pr_title, pr_body, branch_name)
+    print(f"\nPR #{pr_num} created: https://forge.alexanderwhitestone.com/{GITEA_OWNER}/{GITEA_REPO}/pulls/{pr_num}")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/scripts/test_security_patch_applier.py b/scripts/test_security_patch_applier.py
new file mode 100644
index 0000000..db870ef
--- /dev/null
+++ b/scripts/test_security_patch_applier.py
@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+"""Smoke test for security_patch_applier — verifies module imports and argument parsing."""
+import subprocess
+import sys
+
+def test_imports():
+    import security_patch_applier
+    assert hasattr(security_patch_applier, 'main')
+
+def test_help():
+    result = subprocess.run(
+        [sys.executable, 'scripts/security_patch_applier.py', '--help'],
+        capture_output=True, text=True
+    )
+    assert result.returncode == 0
+    assert 'Security Patch Applier' in result.stdout or '--dry-run' in result.stdout
+
+if __name__ == '__main__':
+    test_imports()
+    test_help()
+    print("OK")