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 auditing-http2-and-grpc-multiplexing-trustgit 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/auditing-http2-and-grpc-multiplexing-trust)<a href="https://agentmods.dev/skills/unboundcompute/security-agent-skills/auditing-http2-and-grpc-multiplexing-trust"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/auditing-http2-and-grpc-multiplexing-trust/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/auditing-http2-and-grpc-multiplexing-trust"><img src="https://agentmods.dev/badge/skills/unboundcompute/security-agent-skills/auditing-http2-and-grpc-multiplexing-trust.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 | $0.00193 | $0.02178 |
| Opus 5 | $0.00097 | $0.01089 |
| Sonnet 5 | $0.00039 | $0.00436 |
| Haiku 4.5 | $0.00019 | $0.00218 |
Grade A, and why
auditing-http2-and-grpc-multiplexing-trust 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 11d 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 — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Auditing HTTP/2 and gRPC multiplexing trust: when a stream is not what the connection claims
HTTP/2 and gRPC move the unit of a request from a connection to a stream: one connection carries many interleaved streams, each with its own headers, pseudo-headers, and path. Trust decisions that were written for one-request-per-connection quietly break here. A downgrade seam, HTTP/2 translated to HTTP/1.1 at the origin, or cleartext h2c smuggled past a front end, reintroduces the framing ambiguity of request smuggling in a protocol that was supposed to have solved it. Pseudo-headers like the authority and path are attacker-set per stream, so a stream can claim a path or host the front end never authorized. And per-connection controls, authentication established once, a rate limit counted per connection, are undercounted when many streams share the connection. A gRPC gateway adds method names and metadata a caller controls. The audit asks whether trust is enforced per stream and whether translation preserves the framing. You audit this by testing each stream and each downgrade seam rather than trusting the connection.
When to use
- An edge terminates, downgrades, or translates HTTP/2, including h2c or HTTP/2-to-HTTP/1.1 to an origin.
- gRPC calls are multiplexed on shared connections and authentication or rate limits may be per connection.
- A gRPC gateway trusts caller-supplied metadata, method names, or pseudo-headers to route or authorize.
Scope check
Test HTTP/2 and gRPC edges only on systems you own or are authorized to assess, on non-production endpoints. A downgrade smuggling proof can poison other streams or requests, so use a dedicated test origin and keep payloads benign. If you can't name the authorization, stop.
The loop
- Establish the intended per-stream trust first. Name what each stream should be allowed to do and how authentication, path authorization, and rate limits are meant to apply: per stream, on verified attributes. This is the false-positive killer: an edge that authenticates and authorizes every stream independently on attributes it verifies, and downgrades without reintroducing framing ambiguity, is correct. Name the intended per-stream trust, then test against it.
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.
- 11d ago First seen · 139 lines · 193 tokens per session scan A 36005fb32e6d
auditing-http2-and-grpc-multiplexing-trust is a skill published in the GitHub repository UnboundCompute/security-agent-skills (5 stars, last pushed 2d ago), licensed MIT. It adds 193 tokens to every session and 2,178 once invoked, about $0.0010 per session on Opus 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 2026-08-31.
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