> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/compute/appsec-docker-5.md).

# Update instructions are used alone in a Dockerfile misconfiguration detected in code

## Rule Details

|                        |                                |
| ---------------------- | ------------------------------ |
| Cortex AppSec Rule ID  | APPSEC\_DOCKER\_5              |
| Category - Subcategory | Compute - Startup Script Leaks |
| Provider               | OTHER                          |
| Severity               | LOW                            |
| Framework              | DOCKER                         |

## Impact

This rule detects whether OS package manager update instructions, such as apt-get update or yum update, are used alone within Dockerfiles. Using update instructions alone, or in a single line, causes the update layer to be cached. This can lead to stale updates being used in subsequent builds, preventing necessary updates from being applied and potentially introducing vulnerabilities. Therefore, we recommend that update instructions should always be combined with package installation commands in the same RUN instruction.

## How to Fix

To mitigate this issue, combine the update commands with install commands in a single RUN instruction. This ensures that the package list is updated and packages are installed in the same layer.

## Example: \[source,go]

* RUN apt-get update
* RUN apt-get update && apt-get install -y

***


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/compute/appsec-docker-5.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.