hunting-expression-language-injection SKILL.md skillA
hunting-expression-language-injection 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-expression-language-injection@git:20260826.c45369bPins git:20260826.c45369b 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-expression-language-injection/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260826.c45369b, committed Aug 26, 2026
- Size
- 9,243 bytes
- Repository stars
- 26
- License
- MIT
Hunt expression-language injection where untrusted input reaches a server-side expression evaluator: Spring Expression Language, OGNL, MVEL, JEXL, a Jakarta or JSP EL context, or a rules engine that evaluates strings. Covers request data flowing into an expression compiled and evaluated at runtime, where the language exposes type access, method calls, or a runtime handle that reaches command execution. Use when the application evaluates expressions built from or influenced by untrusted input…
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 expression-language injection: when a string is evaluated as a program Expression languages exist to let configuration, templates, and rules evaluate small snippets at runtime, Spring Expression Language, OGNL, MVEL, JEXL, and the Jakarta and JSP EL contexts among them. Most expose far more than arithmetic: type resolution, method invocation, and a handle to the runtime. When untrusted input is concatenated into, or supplied as, an expression that one of these evaluators compiles, the attacker's text is executed with the evaluator's full power, which typically reaches process execution or reflection. This class caused some of the largest breaches on record. You find it by locating every runtime expression evaluation and asking whether untrusted input shapes the expression rather than only supplying a bound variable. ## When to use - The application evaluates expressions at runtime through an EL, OGNL, MVEL, JEXL, or a rules engine. - Untrusted input is concatenated into an expression string or supplied as an expression to evaluate. - A framework feature (data binding, templating, routing, error pages) evaluates attacker-reachable EL. ## Scope check …
Read the whole file at its exact version.
How to install
mdr add unboundcompute/security-agent-skills/hunting-expression-language-injection@sha256:6bdbcf170967e1e9The line at the top of this page pins the label git:20260826.c45369b, 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_numd2u4qir2wnxue)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Aug 26, 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 (9243 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_numd2u4qir2wnxue GET https://markdownregistry.com/api/v1/resolve?ref=unboundcompute/security-agent-skills/hunting-expression-language-injection GET https://markdownregistry.com/api/v1/blob/6bdbcf170967e1e9fa8c7fd8d1d9c3a2d4917affd2657de0ba6093c0e54a0654
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.