hunting-content-type-and-parser-confusion SKILL.md skillA
hunting-content-type-and-parser-confusion from unboundcompute/security-agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add unboundcompute/security-agent-skills/hunting-content-type-and-parser-confusion@git:20260903.6dac719Pins git:20260903.6dac719 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- unboundcompute/security-agent-skills
- Path
skills/hunting-content-type-and-parser-confusion/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260903.6dac719, committed Sep 3, 2026
- Size
- 9,911 bytes
- Repository stars
- 26
- License
- MIT
Hunt content-type sniffing and parser confusion where untrusted content is served or consumed with an ambiguous or attacker-influenced type, so a browser sniffs a response as HTML, a backend picks a different interpretation than the sender intended, or two parsers on one path disagree. Use when user content is echoed with a missing, wrong, or user-controlled content type, when uploads are typed by extension or by the client, or when a request body can be parsed more than one way. Covers…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Hunting content-type and parser confusion: when two parties disagree on what the bytes are A stream of bytes has no inherent type; something decides whether it is HTML, JSON, an image, or a form. When that decision is ambiguous, the attacker gets to influence it. A browser that sniffs a response ignores a benign declared type and runs the HTML it finds inside. An upload filter that trusts the client type or the extension accepts a script disguised as an image. Two parsers on one path, a permissive multipart reader and a strict one, split a request differently and let content slip past the checker into the sink. A single file that is valid as two formats passes an image check and executes as markup. The bug is never the bytes; it is that the type is resolved by guessing rather than by an authoritative, enforced declaration. You find these by locating where content is typed and asking who decides and whether anyone can be made to disagree. ## When to use - User-controlled content is returned in a response with a missing, generic, or user-influenced type. - Uploads are accepted and typed by client-supplied content type or by file extension rather than content. …
Read the whole file at its exact version.
How to install
mdr add unboundcompute/security-agent-skills/hunting-content-type-and-parser-confusion@sha256:27a4659e6b0ba40eThe line at the top of this page pins the label git:20260903.6dac719, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_mxhm2qahslwkisme)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Sep 3, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (9911 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
unboundcompute/security-agent-skills · 26 stars · license MIT · pushed 2026-09-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_mxhm2qahslwkisme GET https://markdownregistry.com/api/v1/resolve?ref=unboundcompute/security-agent-skills/hunting-content-type-and-parser-confusion GET https://markdownregistry.com/api/v1/blob/27a4659e6b0ba40ecd8233926a515e17cfcc4adade9ebefca6019a2148038df1
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.