eresus-pr-security-review

name	eresus-pr-security-review
description	Security-focused pull request and diff review skill for finding newly introduced vulnerabilities, risky regressions, and missing security tests in changed code. Trigger when the user asks to: "review this PR for security", "check this diff for vulns", "do a security code review", "audit changed files", or wants findings on a patch instead of a full-repo scan. Best used alongside eresus-sast-scanner.
metadata	{"version":"1.0","domain":"application-security","mode":"review"}

Security PR Review

Purpose

Review changed code with a security-review mindset: prioritize introduced bugs, exploitable regressions, and missing coverage in the modified attack surface. Focus on what the diff changes, not on writing a general audit of the whole repository.

Scope Rules

• Prioritize vulnerabilities introduced or exposed by the diff.
• Inspect surrounding code when needed to confirm reachability, auth context, or sanitizer behavior.
• Mention pre-existing issues only when the change makes them reachable, worse, or security-relevant now.
• Findings come first; summary is secondary.

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Workflow

Step 1: Read the Diff as an Attack Surface Change

Identify:

• newly added endpoints, handlers, controllers, jobs, or CLI paths
• changed authorization checks or middleware wiring
• new deserialization, template rendering, file, network, or command execution paths
• config changes that weaken defaults or widen trust boundaries

Step 2: Map New Sources, Sinks, and Guards

For changed code, locate:

• attacker-controlled inputs
• dangerous sinks
• sanitization, validation, auth, and feature-flag guards

Do not stop at the edited hunk if the actual sink or protection lives nearby.

Step 3: Trace Security-Sensitive Data Flow

Apply lightweight taint reasoning through:

• helper calls
• serializers and DTOs
• middleware layers
• ORM/query helpers
• template/view rendering
• background job enqueue/dequeue boundaries

Step 4: Review Diff-Specific Risk Patterns

Pay extra attention to:

• string-built queries, filters, or shell commands
• unsafe deserialization, polymorphic typing, object revival, or parser feature flags
• auth checks moved later in the flow
• newly trusted headers, cookies, or client-supplied role fields
• open redirects added through next, returnTo, or redirect_url
• debug logging of secrets, tokens, or PII
• upload handling, archive extraction, or path joins
• new outbound HTTP fetches or webhook callbacks
• security settings changed from strict to permissive

Step 5: Judge Before Reporting

For every candidate finding, verify:

• the input is actually attacker-controlled
• the changed path is reachable
• protections are not already effective
• the issue is materially exploitable

Drop speculative findings that cannot survive this check.

Step 6: Report Findings and Testing Gaps

Report confirmed issues with:

• severity
• exact changed file and line
• exploit path in one short paragraph
• concrete remediation direction
• missing test coverage if the diff should have added one

If no confirmed issue exists, say so explicitly and note any residual uncertainty or testing gaps.

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Review Guardrails

• Do not file a security finding purely because code "looks risky"; explain the actual exploit path.
• Do not ignore new trust boundaries just because the sink is in an unchanged helper.
• Do not report infra-only assumptions as app bugs unless the diff depends on them.
• Do not downgrade auth bugs simply because the endpoint is "internal" without evidence.
• Do not confuse code-quality concerns with security findings unless they create exploitability.

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Output Format

Use this structure:

[SEVERITY] <short title>
File: <path>:<line>
Why it matters: <reachability + impact in 2-4 sentences>
Fix: <specific remediation>
Tests: <missing or recommended coverage>

When there are no findings:

No confirmed security findings in the reviewed diff.
Residual risk: <short note or "none identified">
Testing gap: <short note or "none identified">