A new security vulnerability, CVE-2025-29819, has been discovered in Microsoft’s Azure Portal, specifically within the Windows Admin Center integration. This vulnerability opens the door to unauthorized attackers who can control file names or paths, leading to local information disclosure. In this exclusive write-up, we’ll walk through what the vulnerability is, how it works, its impact, and give you a demonstration with code, along with links to official resources.

What is CVE-2025-29819?

*CVE-2025-29819* is classified as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')." In simple terms: If you give the wrong file path, attackers might gain access to data they should not see, just by controlling the filename or path in the Azure Portal Windows Admin Center.

How Does the Vulnerability Happen?

The problem starts when Windows Admin Center integrated in Azure Portal allows users to input or select file names or paths for local operations, such as viewing logs or importing data.

Normally, the software should check (sanitize) these inputs. But, with CVE-2025-29819, the validation is insufficient. A user can manipulate the path – using ../ sequences (known as "dot-dot-slash") – to "break out" of the expected directory and access files elsewhere.

Suppose a feature allows an admin to view server logs like this

GET /logs?file=eventlog.txt

An attacker changes the file parameter to something like

GET /logs?file=../../../../Windows/System32/config/SAM

Result: The attacker gains access to the highly sensitive SAM file (Windows Security Accounts Manager), which is NEVER meant to be exposed!

Here’s a simplified snippet that demonstrates how such a vulnerability can exist

// Vulnerable code (Node.js-like pseudocode)
app.get('/logs', (req, res) => {
    const fileName = req.query.file; // User-controlled input
    const logDirectory = 'C:/inetpub/logs/'; // The intended safe directory
    const fullPath = path.join(logDirectory, fileName);
    
    // Reads file and sends content
    fs.readFile(fullPath, (err, data) => {
        if (err) return res.status(404).send('File not found');
        res.send(data);
    });
});

What's wrong?
fileName is never checked for malicious characters (../), so an attacker can reach files outside logDirectory.

Details of the Exploit

1. Find an Input Field: The attacker finds an area in Azure Portal’s Windows Admin Center where a file name or path can be specified (e.g., file downloads, log viewers, diagnostic exports).
2. Inject Malicious Path: Instead of a normal file, they enter something like ../../../Windows/System32/drivers/etc/hosts.
3. Disclosed Data: Sensitive content is then read and shown to the attacker, even if they shouldn’t have permission.

> Note: Exploiting this vulnerability requires local access or interaction with a managed VM, and is thus considered a local information disclosure issue.

Proof of Concept (PoC)

Let’s simulate a request exploiting this vulnerability.

HTTP Request

GET /logs?file=../../../../Windows/System32/win.ini HTTP/1.1
Host: youradmincenter.azure.com
Cookie: sessionid=...

Response from the server might contain

; for 16-bit app support
[fonts]
[extensions]
[mci extensions]

If you see Windows INI file contents, the exploit worked — and you've read from an unauthorized location.

Impact

- Who’s affected? Anyone using Azure Portal with Windows Admin Center integration, until patched.
- Confidential Data Exposure: Attackers could read config files, user tokens, system data, or even secrets if files are accessible.
- Local only: This vulnerability requires local access or a valid session, so it’s not remote code execution, but is still a serious concern for privilege escalation or lateral movement in compromised environments.

Official References

- Microsoft Security Response Center: CVE-2025-29819
- Common Weakness Enumeration: CWE-22
- Microsoft Documentation: Secure file access in web apps

How to Protect Yourself

1. Apply Patches: Microsoft will release or has released updates — install them via Azure Portal update system.
2. Validate Inputs: Never trust user input for file names. Always sanitize using whitelists or path normalization.

Use Path Libraries: Use secure path management and never join paths blindly.

4. Least Privilege: Restrict service permissions to only those directories necessary for operations.

Improved Code Example

// Secure approach
app.get('/logs', (req, res) => {
    let fileName = path.basename(req.query.file); // Only accept filename, not path
    const logDirectory = 'C:/inetpub/logs/';
    const fullPath = path.join(logDirectory, fileName);
    
    fs.readFile(fullPath, (err, data) => {
        if (err) return res.status(404).send('File not found');
        res.send(data);
    });
});

Conclusion

CVE-2025-29819 is a serious, but fixable, flaw in Azure Portal’s Windows Admin Center. If you manage Windows servers in Azure and use admin tools there, you *must* update immediately and audit your file-access code. Path traversal vulnerabilities are easy to miss but can lead to devastating leaks of confidential information.

Stay aware, patch often, and always validate all file paths.

Exclusive content – Written for easy understanding by IT admins of any skill level.
*Share it with your sysadmin friends before your logs leak!*

References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-29819
- https://cwe.mitre.org/data/definitions/22.html
- https://learn.microsoft.com/en-us/azure/app-service/security-best-practices

Timeline

Published on: 04/08/2025 18:16:07 UTC
Last modified on: 05/06/2025 17:03:55 UTC