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CC exploiting-template-injection-vulnerabilities

Detects and exploits Server-Side Template Injection (SSTI) vulnerabilities across Jinja2, Twig, Freemarker, and other template engines to achieve remote code execution. Use when pentesting a web application that renders user input through a server-side template engine and you need to confirm and weaponize SSTI.

mukul975/Anthropic-Cybersecurity-Skills Agent Skills author: mukul975 Apache-2.0 4 files · 1 script body ≈ 2 957 tokens Open the sourcegithub.com↗ analyzed 6 d ago

Detects and exploits Server-Side Template Injection (SSTI) vulnerabilities across Jinja2, Twig, Freemarker, and other template engines to achieve remote code…

As a process C 52/100 · Has gaps — References files that are not bundled: "id",shell=True,stdout=-1, "/etc/passwd"

AnalyzerCommerceSecuritytype and topics are labelled automatically from the skill text
Runs in: Claude / Claude Code ChatGPT / Codex Gemini CLI Cursor GitHub Copilot / VS Code Qwen Code Kimi Code CLI Z.ai (GLM) DeepSeek (Deep Code) Mistral Vibe LangChain (deepagents) OpenClaw Goose OpenCode
JSON
Technical rating
C
86/100
safety, quality, tests
Safety 60%
97
Quality 40%
69
Run on models
none yet
Process rating
C
52/100
Has gaps
References files that are not bundled: "id",shell=True,stdout=-1, "/etc/passwd"
Tools and files w 18
0
Failures and branches w 10
0
Progress reporting w 2
0
the three weakest of ten parameters · all ten

How to improve

  1. The text references files that are not there: add them or drop the references.
For the model run — optional
  • Your own cases (evals/evals.json, 4–6 real requests with expected answers): the full check would then run those instead of a model-drafted suite.
  • A spec.yaml with trigger phrases and assertions — a behaviour contract for CI; `skilltest init` writes a template.

Guard findings · 3

✓ No critical or high findings

Medium and low: 3
  • low Risky intent intent-offensive-security SKILL.md:5
    Offensive-security / dual-use content (legitimate for authorised testing; review intended use)
    code execution. Use when pentesting a web application that renders user input
  • low Risky intent intent-offensive-security SKILL.md:44
    Offensive-security / dual-use content (legitimate for authorised testing; review intended use)
    - **Authorization**: Written penetration testing agreement with RCE testing scope
  • low Risky intent intent-offensive-security SKILL.md:315
    Offensive-security / dual-use content (legitimate for authorised testing; review intended use)
    - Potential lateral movement to internal network

Files scanned: 4. Evidence is masked. Grey chips explain why severity was lowered.

Against the Agent Skills spec

  • warning missing-ref reference to a missing file: "id",shell=True,stdout=-1
  • warning missing-ref reference to a missing file: "/etc/passwd"
  • note frontmatter-key unknown frontmatter key "domain"
  • note frontmatter-key unknown frontmatter key "subdomain"
  • note frontmatter-key unknown frontmatter key "nist_csf"
  • note frontmatter-key unknown frontmatter key "mitre_attack"

Process rating: all ten parameters 52/100

Will not run. References files that are not bundled: "id",shell=True,stdout=-1, "/etc/passwd"
  • 0Tools and files. 2 referenced file(s) missing: "id",shell=True,stdout=-1, "/etc/passwd"
  • 0Failures and branches. Linear process with no failure handling
  • 0Progress reporting. Says nothing while it works
  • 20When it triggers. No condition that starts the skill
  • 60Result and completion. Output format stated, no completion criterion
  • 70Inputs and preconditions. Inputs and preconditions are listed
  • 100Steps. 11 steps
  • 100Consistency. Name and required fields are in place
  • 100Execution cost. Instruction body is 2957 tokens
  • 100Running it twice. No mutating operations

Everything here is measured from the skill text rather than judged by a model, so the numbers are checkable. A parameter weighs more when it is a more common reason for the process to stall.

Quality signals

  • +5Description has no quoted example phrases that should trigger the skill
  • +4Description does not say when NOT to use the skill (false activations)
  • -41 reference files, but SKILL.md never points to them: the model will not open them
  • -31 of 1 scripts are never mentioned in SKILL.md
  • +2Single-language instructions
  • +3Description length 312: enough signal without eating the budget
  • +4Structure: 18 headings
  • +3Step-by-step instructions: 11 items
  • +3Output format is stated explicitly
  • +4Has examples (7 code blocks)
  • +1License stated

Quality base 70; lint remarks subtract, signals add up to 100. Result: 69.