Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add UnboundCompute/security-agent-skills --skill hunting-server-side-rendering-and-svg-image-abusegit clone --depth 1 https://github.com/UnboundCompute/security-agent-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/unboundcompute/security-agent-skills/hunting-server-side-rendering-and-svg-image-abuse)<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/hunting-server-side-rendering-and-svg-image-abuse"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/hunting-server-side-rendering-and-svg-image-abuse/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/hunting-server-side-rendering-and-svg-image-abuse"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/hunting-server-side-rendering-and-svg-image-abuse.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00164 | $0.02185 |
| Opus 5.5 | $0.00066 | $0.00874 |
| Sonnet 5.5 | $0.00033 | $0.00437 |
| Haiku 4.5 | $0.00016 | $0.00218 |
Grade A, and why
hunting-server-side-rendering-and-svg-image-abuse scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Hunting server-side rendering and SVG image abuse: when generating a document fetches the attacker's URL
To turn a user's content into a PDF, a screenshot, or a thumbnail, a server hands markup or a URL to a renderer, and a renderer is a small browser: it resolves links, loads images, follows redirects, and often runs script and reads local files. When that content is attacker-controlled, the renderer becomes a request engine operating from inside the network, fetching an internal address or cloud-metadata endpoint, reading a local file through a file scheme or an external entity, calling out to a host that proves the render happened, or executing script that reads the rendered page. The bug is not the markup; it is a renderer left free to resolve whatever the document points at, running server-side with network and file reach the user never should have. You find these by locating every server-side render of untrusted content and reading what the renderer is allowed to resolve.
When to use
- A service renders user-supplied HTML or SVG server-side into a PDF, an image, a screenshot, or a preview.
- A thumbnailer, chart generator, or document converter processes untrusted files or URLs on the server.
- A feature fetches and renders a user-supplied URL to produce a preview, an archive, or an export.
Scope check
Test server-side rendering only against systems you own or are authorized to assess, on non-production infrastructure, using benign local markers and a destination you control for any fetch, never pulling real secrets or reaching third-party addresses. A confirmed case reaches internal services, so keep every probe inside the authorized scope and prefer an isolated instance. If you can't name the authorization, stop.
The loop
- Establish what the renderer is allowed to resolve first. For each renderer, determine whether it will fetch remote URLs, follow redirects, resolve local-file schemes, load external entities, and execute script, or whether it runs sandboxed with the network disabled, external subresources blocked, and script off. This is the false-positive killer: a renderer that resolves nothing external cannot be driven to fetch a URL or read a file no matter what the document contains, so name the renderer's capabilities before crafting a document.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 141 lines · 164 tokens per session scan A fa5503fb0c05
hunting-server-side-rendering-and-svg-image-abuse is a skill published in the GitHub repository UnboundCompute/security-agent-skills (5 stars, last pushed 1mo ago), licensed MIT. It adds 164 tokens to every session and 2,185 once invoked, about $0.0007 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-05.
Other skills, from other repositories
prodcheck-review
Review this codebase against the prodcheck pre-production checklists — security, performance, scale, integrations, post-launch readiness and people. Use when asked to check whether a project is ready to ship, to audit an area before launch, or to work through a specific checklist. Produces evidence with file:line…
integrate-arcjet-guard-genkit
Integrate Arcjet security into a Genkit JS agent using @arcjet/guard — wrap ai.defineTool, put guardMiddleware on generate({ use }) for unwrapped / MCP / filesystem tools, and read a caller-owned id from generate({ context }). Use when asked to add Arcjet to genkit, rate limit its tools, screen inbound messages, or…
integrate-arcjet-guard-tanstack-ai
Integrate Arcjet security into a TanStack AI chat() app using @arcjet/guard — put guardMiddleware first on chat({ middleware }) so onBeforeToolCall gates tools, and read a caller-owned id from chat({ context }). Use when asked to add Arcjet to TanStack AI, rate limit its tools, screen inbound messages, or block prompt…
integrate-arcjet-guard-claude-managed-agents
Integrate Arcjet security into Claude Managed Agents (hosted REST+SSE, beta managed-agents-2026-04-01) using @arcjet/guard — screen user.message / initialevents before sessions.events.send, and gate custom tools on agent.customtooluse. Use when asked to add Arcjet to Claude Managed Agents, rate limit custom tools, or…
linear-claude-skill
Manage Linear issues, projects, and teams.
varlock-claude-skill
Secure environment variable management ensuring secrets are never exposed in Claude sessions, terminals, logs, or git commits.