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CVE-2021-36766

24
FAUCET Score

CVE-2021-36766 is a critical deserialization vulnerability affecting Concrete5 through version 8.5.5, specifically within the Logging::update_logging() method. This flaw allows authenticated attackers to inject arbitrary PHP objects via the logFile parameter, leading to potential remote code execution. With a CVSS score of 7.2 (HIGH), it presents a significant risk due to its low attack complexity and high impact on confidentiality, integrity, and availability. There is currently no public exploit code available, nor is it known to be actively exploited in the wild, and it has received minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 8.5.6CPE matchmatch criteria
cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.2HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.2
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.68%
Probability of exploitation in next 30 days
EPSS Percentile
88.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0368 is in the 87th percentile among its peer group of 5,537 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.3 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

packetstormsecurity.com / files/163564/Concrete5-8.5.5-Phar-Deserialization.html
ExploitThird Party AdvisoryVDB Entry
seclists.org / fulldisclosure/2021/Jul/36
ExploitMailing ListThird Party Advisory
hackerone.com / reports/1063039
Permissions RequiredThird Party Advisory