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SECURITY.md

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+# Security Policy
+
+## Supported Versions
+
+Local CI is in pre-release development. There are no tagged stable releases yet
+(`pyproject.toml` declares `0.1.0`, not yet tagged).
+
+Security fixes are produced only against the latest commit on the
+[`develop`](https://github.com/cppalliance/local-ci-test-system/tree/develop)
+branch. Once a `v0.1.0` tag is cut, this section will be reformatted as a
+semver-style support table.
+
+## Reporting a Vulnerability
+
+**Please do not open a public GitHub issue for security vulnerabilities.**
+
+Report security issues through **[GitHub private vulnerability reporting](https://github.com/cppalliance/local-ci-test-system/security/advisories/new)** (preferred), or email **will@cppalliance.org** if you do not have a GitHub account.
+
+If you need an encrypted channel, mention this in your initial email and a
+maintainer will reply with a current PGP key fingerprint or arrange another
+secure channel.
+
+Include as much of the following as you can:
+
+- A description of the vulnerability and its impact
+- Steps to reproduce or a proof-of-concept
+- Affected version(s) or commit range
+- Any proposed mitigation or fix
+
+You can expect an acknowledgement within **5 business days** and a resolution or status update within **90 days**.
+
+For confirmed vulnerabilities with user impact, CppAlliance maintainers will
+request a CVE through GitHub's CNA on your behalf and credit you in the
+advisory unless you ask to remain anonymous.
+
+## Scope
+
+The following classes of vulnerability are **in scope**:
+
+| Category                            | Examples                                                                                                         |
+| ----------------------------------- | ---------------------------------------------------------------------------------------------------------------- |
+| Container escape                    | Breakout from Docker containers spawned by `localci run`                                                         |
+| Token / secret exposure             | CI tokens, Docker registry credentials, or `.localci.yml` secrets leaked to logs, temp files, or child processes |
+| Path traversal                      | Workflow YAML or config paths that escape the project root                                                       |
+| Dependency confusion / supply chain | Malicious images resolved by the image-scoring algorithm                                                         |
+| Privilege escalation                | Commands that gain unintended host-level access via Docker socket                                                |
+
+Issues with the act runner itself, Docker Engine, or other external prerequisites should be reported to their respective projects unless the vulnerability is triggered specifically by Local CI's orchestration of those tools.
+
+## Out of Scope
+
+- Vulnerabilities in third-party dependencies (act, Docker, yq) that are not amplified by Local CI
+- Resource-exhaustion or crash issues with no privilege escalation, sandbox
+  escape, or data-exfiltration consequence
+- Theoretical vulnerabilities without a realistic attack scenario