Executive Summary

CVE-2026-29058 is a critical unauthenticated OS command injection vulnerability in the AVideo-Encoder project affecting versions prior to 7.0. It occurs in the `objects/getImage.php` script where the `base64Url` GET parameter is Base64-decoded and directly inserted into a shell command without proper escaping. This allows an attacker to inject shell command substitutions that the server executes.

The vulnerability arises because the application uses asynchronous command execution functions like `shell_exec` and `nohup` with unescaped user input, leading to improper neutralization of special elements in OS commands (CWE-78). Despite URL syntax validation, shell metacharacters can still be executed.

An attacker can exploit this remotely without authentication or user interaction, enabling arbitrary OS command execution on the server.

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Impact Analysis

Exploitation of this vulnerability can lead to full server compromise, allowing attackers to execute arbitrary operating system commands.

• Data exfiltration of sensitive information such as configuration secrets, internal keys, and credentials.
• Service disruption due to unauthorized command execution.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability exists in the `objects/getImage.php` script where the `base64Url` GET parameter is used unsafely in shell commands. Detection can involve monitoring or testing for command injection attempts via this parameter.'}, {'type': 'paragraph', 'content': 'You can attempt to detect exploitation by sending crafted requests to the vulnerable endpoint that include shell command substitution sequences encoded in the `base64Url` parameter and observe if arbitrary commands execute.'}, {'type': 'list_item', 'content': 'Use curl or similar tools to send requests with payloads designed to trigger command execution, for example:'}, {'type': 'list_item', 'content': "curl 'http://yourserver/objects/getImage.php?base64Url=$(id)'"}, {'type': 'list_item', 'content': "curl 'http://yourserver/objects/getImage.php?base64Url=$(cat /etc/passwd)'"}, {'type': 'paragraph', 'content': 'Monitoring logs for unusual command execution or unexpected output from the `getImage.php` endpoint can also help detect exploitation attempts.'}] [1]

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Mitigation Strategies

The vulnerability has been fixed in AVideo version 7.0. The immediate recommended step is to upgrade to version 7.0 or later.

Until you can apply the patch, you should restrict access to the vulnerable `objects/getImage.php` endpoint using web server or reverse proxy controls such as IP allowlisting or authentication.

Applying Web Application Firewall (WAF) rules to block suspicious input patterns targeting the `base64Url` parameter can reduce exposure.

Avoid using the vulnerable versions in production environments and monitor for any suspicious activity related to this endpoint.

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