CVE-2025-27784 - Applio Arbitrary File Read Leads to SSRF Data Exfiltration

Published: June 2024
Author: [Your Name]

Overview

Applio is an open-source voice conversion toolkit, popular among hobbyists and professionals seeking to transform and manipulate voice data. On June 15, 2024, a critical vulnerability—CVE-2025-27784—was disclosed, affecting Applio versions 3.2.8-bugfix and prior. This issue allows attackers to read arbitrary files on the Applio server by exploiting insecure handling in the train.py script's export_pth function. More dangerously, this can expose sensitive data on the internal network via blind Server-Side Request Forgery (SSRF).

No official patch or mitigation exists at the time of this writing. Users should strongly consider restricting access to affected Applio instances.

What’s the Root Cause?

Applio’s export_pth function in train.py unsafely processes user input, allowing attackers to specify arbitrary file paths. This is a classic case of improper input validation, commonly leading to information disclosure vulnerabilities.

Attack Surface

If an attacker can send requests to the Applio server (such as having access to its web interface or API), they can exploit this flaw.

Vulnerable Function

In Applio's train.py, the function export_pth is responsible for handling model checkpoint exports. Here's a simplified snippet of the problem area:

def export_pth(src, out):
    with open(src, "rb") as fin:
        data = fin.read()
    with open(out, "wb") as fout:
        fout.write(data)

src and out are user-controlled.

- No sanity checks are made on the path—filesystem traversal (like ../../etc/passwd) is possible.
- If src is a path like /etc/passwd, the target file's contents can be captured and stored at a path chosen by the attacker.


### Attack Example #1: Read /etc/passwd on Linux

Suppose the server hosts a web endpoint that ultimately passes parameters to export_pth. The attacker submits:

- src: /etc/passwd
- out: /tmp/stolen_passwd

If the attacker can later fetch /tmp/stolen_passwd, they now have /etc/passwd's content.

Attack Example #2: SSRF File Read

Because export_pth may also handle paths like URLs (e.g., if underlying code supports Python's open() with HTTP(S) URLs via urllib patching or similar), this can turn into a blind SSRF tool:

- src: http://internal-service.local/secret-config.yaml
- out: /tmp/dumped_config

Even if Applio is *not* directly exposed to the public, an attacker with access could steal internal-only files, proving especially dangerous for cloud or enterprise setups.

How Dangerous Is This?

- Data Breach: Attackers can exfiltrate sensitive information from both local disk and potentially reachable network files.
- Lateral Movement: Internal files (e.g., AWS credentials, .env secrets, configs) might allow further attacks.
- Persistence/Elevation: If write permissions are broad, attackers may even overwrite files or drop backdoors.

Code Review: If you maintain a fork, sanitize file paths and reject URLs or traversal attempts.

- Containerization: Consider running Applio in a sandboxed environment with minimal file privileges.

Resources & References

- CVE-2025-27784 at NVD (Pending) *(Not live at time of writing)*
- Applio GitHub Repository
- OWASP Path Traversal
- SSRF Exploitation Guide

Conclusion

CVE-2025-27784 is a critical flaw in popular voice tech software Applio, making arbitrary file reading trivial for those with access to its interfaces. The added risk of SSRF means isolated networks are *not* safe if Applio reaches internal resources. With no fix in sight, users should strictly limit access and consider reviewing their deployment immediately.


Stay Safe. Spread the Word. For questions or updates, check the Applio repo.

Timeline

Published on: 03/19/2025 21:15:40 UTC