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Security audit

Skyvern

Security checks for vulnerabilities and agentic risk

Overview

The Skyvern actions have clear approval rules, but automatic setup can execute unreviewed remote code and introduce broader persistent agent changes.

Review and approve CLI installation separately, including whether it installs or synchronizes other agent skills. Use a reviewed, pinned CLI version and confirm browser-task payloads and cancellations. OOMOL intermediates your Skyvern account access. The remote installer and live connector implementation were not bundled, so their complete behavior remains unverified.

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
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
  • Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
  • Output HandlingUnvalidated Output Injection, Cross-Context Output, Unbounded Output
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Findings (4)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
99% confidence
Finding

The supplied code performs remote installer execution rather than Skyvern data operations. Nothing in the chunk establishes that this installer is a supporting dependency for Skyvern. The downloaded script's contents are not supplied, so its additional behavior cannot be assessed.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
99% confidence
Finding

Piping a mutable remote script directly into Bash executes its contents without verifying a pinned artifact or reviewing the code first. HTTPS protects transport but does not prevent a compromised installer host or publishing pipeline from delivering code that could access local files and credentials; the legitimate dependency context and conditional fallback reduce exposure but do not eliminate this risk.

Content

Scanner excerpt · SKILL.md (reported line 58)May include surrounding context.

First-time setup instructs the agent to execute remotely downloaded installer scripts without warning about system changes.

Medium
Category
Output Handling
Confidence
96% confidence
Finding

The fallback setup directs execution of remotely downloaded shell or PowerShell scripts without requiring explicit installation approval or explaining local system changes. Although limited to a missing-CLI error, this turns a Skyvern request into potential local code execution with the invoking user's privileges.

Content

No source excerpt is available for this finding.

Autonomous Decision Making

Medium
Category
Excessive Agency
Confidence
80% confidence
Finding

Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Content

Scanner excerpt · SKILL.md (reported line 79)May include surrounding context.

md
- **`OOMOL_INSUFFICIENT_CREDIT`** — OOMOL billing stop. Recharge at `https://console.oomol.com/billing/token-recharge` before retrying.

- **HTTP 402 without `OOMOL_INSUFFICIENT_CREDIT`** — the third-party account itself has no active plan or credit. Report the provider error message as is; do not ask the user to recharge OOMOL.

## Resources