GitHub Security Advisory: GHSA-54m3-5fxr-2f3j
Package: salvo (RUST)
Severity: HIGH (CVSS 8.8)
CWE: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Vulnerable versions: < 0.88.1
Patched in: 0.88.1

Summary: Salvo is vulnerable to stored XSS in the list_html function by uploading files with malicious names

Details:
# Summary

The function `list_html` generates a file view of a folder without sanitizing the files or folders names, potentially leading to XSS in cases where a website allows access to public files using this feature, allowing  anyone to upload a file.

# Details

The vulnerable snippet of code is the following:
[**dir.rs**](https://github.com/salvo-rs/salvo/blob/16efeba312a274739606ce76366d[PII_REDACTED]54/crates/serve-static/src/dir.rs#L581)

```rust
// ... fn list_html(...
        let mut link = "".to_owned();
        format!(
            r#"<a href="/">{}</a>{}"#,
            HOME_ICON,
            segments
                .map(|seg| {
                    link = format!("{link}/{seg}");
                    format!("/<a href=\"{link}\">{seg}</a>")
                })
                .collect::<Vec<_>>()
                .join("")
        )
// ...
```

# PoC

https://github.com/user-attachments/assets/1e161e17-f033-4cc4-855b-43fd38ed1be4

Here is the example app we used:

`mian.rs`
```rs
use salvo::prelude::*;
use salvo::serve_static::StaticDir;
use std::path::PathBuf;
use tokio::fs;

const INDEX_HTML: &str = r#"<!doctype html>
<html>
  <head><meta charset="utf-8"><title>StaticDir PoC</title></head>
  <body>
    <h2>Upload a file</h2>
    <form action="/upload" method="post" enctype="multipart/form-data">
      <input type="file" name="file" />
      <button type="submit">Upload</button>
    </form>

    <p>Browse uploads:</p>
    <ul>
      <li><a href="/files">/files</a></li>
      <li><a href="/files/">/files/</a></li>
    </ul>
  </body>
</html>
"#;

#[handler]
async fn index(res: &mut Response) {
    res.render(Text::Html(INDEX_HTML));
}

#[handler]
async fn upload(req: &mut Request, res: &mut Response) {
    fs::create_dir_all("uploads").await.expect("create uploads dir");

    let form = match req.form_data().await {
        Ok(v) => v,
        Err(e) => {
            res.status_code(StatusCode::BAD_REQUEST);
            res.render(Text::Plain(format!("form_data parse failed: {e}")));
            return;
        }
    };

    let Some(file_part) = form.files.get("file") else {
        res.status_code(StatusCode::BAD_REQUEST);
        res.render(Text::Plain("missing file field (name=\"file\")"));
        return;
    };

    let original_name = file_part.name().unwrap_or("upload.bin");

    let mut dest = PathBuf::from("uploads");
    dest.push(original_name);

    let tmp_path = file_part.path();
    if let Err(e) = fs::copy(tmp_path, &dest).await {
        res.status_code(StatusCode::INTERNAL_SERVER_ERROR);
        res.render(Text::Plain(format!("save failed: {e}")));
        return;
    }

    res.render(Text::Plain(format!(
        "Uploaded as: {original_name}\nNow open: http://127.0.0.1:5800/files/\n"
    )));
}

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt().init();
    fs::create_dir_all("uploads").await.expect("create uploads dir");

    let router = Router::new()
        .get(index)
        .push(Router::with_path("upl