CVE-2021-36766

Name: CVE-2021-36766
Creator: NVD / NIST
Published: 2021-07-30T14:15:18.283+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.2/10EPSS 3.68%

Last modified Jun 17, 2026

CVE-2021-36766 is a high-severity vulnerability rated 7.2/10 on the CVSS scale. 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. EPSS estimates a 3.68% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.2/10

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.68%

88.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-502

Affected Software

Vendor	Product	Versions
Concretecms	Concrete Cms	< 8.5.6

References

http://packetstormsecurity.com/files/163564/Concrete5-8.5.5-Phar-Deserialization.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2021/Jul/36Exploit, Mailing List, Third Party Advisory
https://hackerone.com/reports/1063039Permissions Required, Third Party Advisory
http://packetstormsecurity.com/files/163564/Concrete5-8.5.5-Phar-Deserialization.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2021/Jul/36Exploit, Mailing List, Third Party Advisory
https://hackerone.com/reports/1063039Permissions Required, Third Party Advisory

Timeline

Published: Jul 30, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-36766?

How severe is CVE-2021-36766?

CVE-2021-36766 has a CVSS score of 7.2/10 (HIGH severity). The EPSS model estimates a 3.68% probability of exploitation in the next 30 days.

How do I fix CVE-2021-36766?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-36766?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST