YAML Injection
Definition
YAML injection manipulates YAML processing through injected data or structural elements.
A vulnerability class where untrusted data influences YAML structure or parser objects to bypass rules or trigger dangerous deserialization.
Simply explained
Foreign input is mistakenly interpreted as part of the configuration. This can undesirably alter its structure or processing.
Why it matters in practice
The term contributes to secure, maintainable, and high-performance web applications as well as resilient technical decisions.
Example from business
A service uses Safe Loader, fixed schemas, and separate data fields instead of YAML text concatenation.
Limits and pitfalls
- String escaping alone is insufficient; tag resolution, alias limits, and library mode are crucial.
Origin & history
Unsafe object-capable deserialization made YAML parsers in multiple languages an attack vector.
Use in mid-sized companies
- Possible example: A service uses Safe Loader, fixed schemas, and separate data fields instead of YAML text concatenation.
Frequently asked questions
What does YAML injection mean?
A vulnerability class where untrusted data influences YAML structure or parser objects to bypass rules or trigger dangerous deserialization. What should be considered? String escaping alone is insufficient; tag resolution, alias limits, and library mode are crucial.
Sources
- Deserialization Cheat Sheet · OWASP, Deserialization Cheat Sheet
Source checked on 10.10.2026. Editorial usage examples are hypothetical; no evidence of real customer results.
Editorially reviewed on: