tessl-labs/skills-security-audit
Audit installed tessl skills for security risks and generate a formatted security report with per-skill risk levels and an overall project risk score
94
Quality
94%
Does it follow best practices?
Impact
Pending
No eval scenarios have been run
Advisory
Suggest reviewing before use
Security
2 findings — 2 medium severity. This skill can be installed but you should review these findings before use.
W011: Third-party content exposure detected (indirect prompt injection risk)
What this means
The skill exposes the agent to untrusted, user-generated content from public third-party sources, creating a risk of indirect prompt injection. This includes browsing arbitrary URLs, reading social media posts or forum comments, and analyzing content from unknown websites.
Why it was flagged
Third-party content exposure detected (high risk: 0.90). The skill's SKILL.md Step 2 requires the agent to fetch and parse security pages from the public Tessl Registry (e.g., https://tessl.io/registry/... and https://tessl.io/registry/skills/github/...), using WebFetch to extract Snyk scores and findings that the agent then uses to form verdicts, so it clearly ingests untrusted third-party web content that could embed instructions or influence behavior.
W012: Unverifiable external dependency detected (runtime URL that controls agent)
What this means
The skill fetches instructions or code from an external URL at runtime, and the fetched content directly controls the agent’s prompts or executes code. This dynamic dependency allows the external source to modify the agent’s behavior without any changes to the skill itself.
Why it was flagged
Potentially malicious external URL detected (high risk: 0.90). At runtime the skill explicitly uses WebFetch to retrieve registry pages like https://tessl.io/registry/{workspace}/{tile}/security and https://tessl.io/registry/skills/github/{org}/{repo}/{skill-name}/security and injects those fetched findings directly into the agent's report, so remote content can control the model's output.
- Audited
- Security analysis