# Zero-Day CVE and Package Deprecation Feeds for Autonomous Coding Harnesses

Published: 2026-10-18 | Domain: https://agentfeeds.si | Feed Endpoint: https://agentfeeds.si/v1/feeds/cve-deltas.json

## Outcome first: blocking vulnerable and deprecated patterns at preflight

Language models frequently emit code using library versions that were popular during pretraining but have since been deprecated or disclosed as vulnerable. When we evaluated unassisted `gemma4:31b` on secure coding tasks in our Harmony benchmark ([harmony.baltor.ai](https://harmony.baltor.ai)), only `31.2%` of generated solutions were jointly functional and free of exploitable weaknesses such as `CWE-918` (Server-Side Request Forgery) or `CWE-89` (SQL Injection). Subscribing the harness to a pull-time CVE and deprecation delta stream raises joint safe-and-functional completion to `82.5%` with zero proof-of-concept exploits passing the verifier.

## Why static pretraining cutoffs fail on security advisories

Even if a model's weights are updated quarterly, two gaps remain:

1. **Newly disclosed CVEs in transitive dependencies**: An agent scaffolding a Python or Node service will pin a package range from its training corpus unless a pull-time feed overrides the minimum safe version.
2. **Silent API deprecations**: In rapidly moving libraries such as Three.js (`r170+` to `r186`), Godot 4.x, or MCP SDKs, removed methods cause immediate runtime crashes that waste three or four retry turns.

```python
# Preflight Dependency & AST Deprecation Gate driven by agentfeeds.si delta stream
def verify_against_cve_delta_feed(ast_imports: list[tuple[str, str]], symbols_used: set[str], delta_feed: dict) -> list[dict]:
    refusals = []
    for pkg, version in ast_imports:
        advisory = delta_feed["packages"].get(pkg)
        if advisory and version < advisory["min_safe_version"]:
            refusals.append({
                "refusal_code": "vulnerable_dependency_version",
                "package": pkg,
                "found": version,
                "required_min": advisory["min_safe_version"],
                "cve": advisory["cve_id"]
            })
    for sym in symbols_used:
        if sym in delta_feed["deprecated_symbols"]:
            info = delta_feed["deprecated_symbols"][sym]
            refusals.append({
                "refusal_code": "deprecated_api_symbol_refused",
                "symbol": sym,
                "replacement": info["replacement"]
            })
    return refusals
```

## Pull-time recheck before external effects

In Loop Engine, a previously cached feed entry never grants permanent execution authority. When a Solution Loop prepares to install a dependency or execute a network tool call, the harness checks the `expires_at` and `revocation_seq` fields on the delta stream so revoked packages are refused before any shell or network effect occurs.