Self-Hosted LLM Security In A Bank: A Worked Example After The 28 October vLLM Advisories

"""Check a self-hosted model server's deployment record before it goes live inside the bank.

vLLM published advisories on 28 October 2026, fixed in 0.32.0, including permissive default CORS origins
(CVE-2026-115917), Ghostscript RCE from untrusted EPS inputs (CVE-2026-115915) and forged multimodal
shared-memory handles reaching pickle.loads (CVE-2026-115912). The record fields below are our own
deployment record, not vLLM option names. Python 3.14 standard library only.
"""
from __future__ import annotations

MIN_VERSION = (0, 32, 0)


def version(v: str) -> tuple[int, ...]:
    return tuple(int(p) for p in v.split(".")[:3])


def lint(rec: dict[str, object]) -> list[str]:
    issues = []
    if version(str(rec["version"])) < MIN_VERSION:
        issues.append(f"version {rec['version']} is below 0.32.0, which fixes the 28 October advisories")
    if "*" in list(rec.get("cors_origins", ["*"])):  # type: ignore[arg-type]
        issues.append("CORS allows any origin: list the internal UI origin explicitly")
    if rec.get("bind") == "0.0.0.0" and not rec.get("behind_gateway"):
        issues.append("listening on all interfaces without an authenticating gateway")
    if not rec.get("api_key_required"):
        issues.append("no API key required on the model server")
    if rec.get("multimodal_inputs") and not rec.get("multimodal_needed"):
        issues.append("multimodal inputs enabled but not needed: switch them off")
    return issues


if __name__ == "__main__":
    pilot = {"version": "0.31.2", "cors_origins": ["*"], "bind": "0.0.0.0", "behind_gateway": False,
             "api_key_required": False, "multimodal_inputs": True, "multimodal_needed": False}
    fixed = {"version": "0.32.0", "cors_origins": ["https://ops-ui.internal"], "bind": "10.20.0.15",
             "behind_gateway": True, "api_key_required": True, "multimodal_inputs": False}
    for name, rec in (("pilot", pilot), ("release candidate", fixed)):
        found = lint(rec)
        print(f"{name}: {'PASS' if not found else 'FAIL'}")
        for i in found:
            print("  -", i)

Python 3.14.4, standard library only. Run once as shown. The record fields are our own deployment record, not vLLM option names.

"""Rollout gate for a model change inside a bank: evaluation passed, latency within budget, and a named
approver, all written to a hash-chained change log before the new model serves the desk.
Python 3.14 standard library only. Sample timings and results only.
"""
from __future__ import annotations

import hashlib
import json
import statistics

LOG: list[dict[str, object]] = []


def record(**entry: object) -> None:
    prev = str(LOG[-1]["hash"]) if LOG else "0" * 64
    body = {**entry, "prev": prev}
    LOG.append({**body, "hash": hashlib.sha256(json.dumps(body, sort_keys=True).encode()).hexdigest()})


def p95(ms: list[float]) -> float:
    return statistics.quantiles(ms, n=20)[-1]


def gate(change: str, eval_passed: bool, timings_ms: list[float], budget_ms: float, approver: str | None) -> bool:
    latency = round(p95(timings_ms), 1)
    reasons = [r for r, bad in [("evaluation not passed", not eval_passed),
                                (f"p95 {latency} ms over {budget_ms} ms budget", latency > budget_ms),
                                ("no named approver", approver is None)] if bad]
    record(change=change, eval_passed=eval_passed, p95_ms=latency, approver=approver,
           decision="refused" if reasons else "released", reasons=reasons)
    return not reasons


if __name__ == "__main__":
    fast = [420, 455, 470, 480, 510, 515, 530, 545, 560, 590, 610, 640, 650, 700, 720, 760, 780, 800, 820, 905]
    slow = [t * 1.6 for t in fast]
    print("CHG-3101:", gate("CHG-3101", True, slow, budget_ms=1200, approver="model.risk@example.co.uk"))
    print("CHG-3102:", gate("CHG-3102", True, fast, budget_ms=1200, approver=None))
    print("CHG-3103:", gate("CHG-3103", True, fast, budget_ms=1200, approver="model.risk@example.co.uk"))
    for e in LOG:
        print(f"  {e['change']} {e['decision']:<9} p95={e['p95_ms']} {e['reasons']} {str(e['hash'])[:10]}")

Python 3.14.4, standard library only. Run once as shown. Sample timings and results.