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Security audit

myhotlunchbox-mcp

Security checks for vulnerabilities and agentic risk

Overview

The skill openly documents account changes and payments that fit its school-lunch management purpose, with clear cautions about their risks.

This skill can change orders, remove students, alter subscriptions, and charge a saved card. Review each requested change and payment total. Write payloads are untested, and omitted fields can erase values. Enter credentials privately and protect downloaded student and transaction files. Both bundled files were inspected; live API behavior and the separate MCP server were not verified.

Vulnerability Patterns
  • Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
  • Agent Memory PoisoningWrites attacker-controlled rules into memory that affect later sessions
  • Remote Payload Retrieval and ExecutionFetches external code whose behavior can change after review
  • Embedded Malicious CodeShips malicious scripts inside the skill and executes them locally
  • Unauthorized Access and Privilege EscalationObtains permissions beyond the task's legitimate needs
Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
Findings (6)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
87% confidence
Finding

The code uses the expected service and shell tooling, but its primary action is an account-changing order submission. Although the description broadly says 'manage,' its concrete capabilities describe reading and checking data and do not disclose order creation. Editing quantities is only a comment; the actual executable behavior is fetching and submitting the order payload.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
85% confidence
Finding

The POST to /payment/initCheckout initiates a checkout workflow. Although the description broadly says 'manage,' its listed payment capability is checking payments, not initiating checkout. This is an additional transactional capability. The snippet does not establish that payment is completed or funds are charged.

Content

No source excerpt is available for this finding.

External Transmission

Medium
Category
Data Exfiltration
Confidence
60% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · SKILL.md (reported line 65)May include surrounding context.

md
# The lunch calendar for a date range (POST, despite being a read).
# The fields are `start`/`end`. Using `startDate`/`endDate` returns 200 with an
# EMPTY events array — a silent wrong answer, not an error.
curl -sS -X POST "$MHLB/api/calendar/studentSchoolData" \
  -H "Authorization: Bearer $MHLB_TOKEN" -H 'Content-Type: application/json' \
  -d '{"start":"2026-09-01","end":"2026-09-30"}' | jq '.events[] | {studentId, id, start, className}'

External Transmission

Medium
Category
Data Exfiltration
Confidence
60% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · SKILL.md (reported line 84)May include surrounding context.

sh
mhlb_get '/event/createOrder?eventId=123&studentId=456' > order.json
# edit quantities in order.json
curl -sS -X POST "$MHLB/api/event/createOrder" \
  -H "Authorization: Bearer $MHLB_TOKEN" -H 'Content-Type: application/json' \
  -d @order.json

External Transmission

Medium
Category
Data Exfiltration
Confidence
60% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · references/endpoints.md (reported line 31)May include surrounding context.

md
# Lunch calendar for a range — a POST that reads
mhlb_post() {
  local endpoint=$1; shift   # NOT `path`: zsh ties $path to $PATH
  curl -sS -X POST "$MHLB/api$endpoint" -H "Authorization: Bearer $MHLB_TOKEN" \
    -H 'Content-Type: application/json' -d "${1:-{\}}"
}

External Transmission

Medium
Category
Data Exfiltration
Confidence
60% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · references/endpoints.md (reported line 87)May include surrounding context.

sh
mhlb_pdf() {  # usage: mhlb_pdf <endpoint> <json> <out.pdf>
  curl -sS -X POST "$MHLB/api$1" -H "Authorization: Bearer $MHLB_TOKEN" \
    -H 'Content-Type: application/json' -d "$2" -o "$3" && file "$3"
}