CVE-2026-8205: concrete cms (CVSS 5.3)

Description

Concrete CMS 9.5.0 and below is vulnerable to authorization bypass in the Calendar Block since action_get_events does not check canView on the calendar which results in restricted event details being disclosed. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks lalalala5678 for reporting.

Is your site exposed to CVE-2026-8205?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.3

MEDIUM

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

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-425 CWE-425

Affected Products

Vendor	Product	Versions
concretecms	concrete_cms	< 9.5.0

References

Other References

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes

Frequently Asked Questions

What is CVE-2026-8205? +

Concrete CMS 9.5.0 and below is vulnerable to authorization bypass in the Calendar Block since action_get_events does not check canView on the calendar which results in restricted event details being disclosed. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks lalalala5678 for reporting. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-8205? +

CVE-2026-8205 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-8205? +

CVE-2026-8205 affects products from concretecms, specifically: concrete_cms. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-8205? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-1542

Improper permission control vulnerability in the OXARI ServiceDesk application could allow an attacker using a guest access or an unprivileged …

CVE-2025-65011

In WODESYS WD-R608U router (also known as WDR122B V2.0 and WDR28) an unauthorised user can view configuration files by directly …

CVE-2026-34028

The Wertheim SafeController Software, AssemblyVersion 6.15.8328.28014, exposes web-accessible file paths that are not protected by an authorization scheme. An unauthenticated …

CVE-2025-26381

Successful exploitation of this vulnerability could allow an attacker to gain unauthorized access to sensitive information.

CVE-2024-0204 9.8

Authentication bypass in Fortra's GoAnywhere MFT prior to 7.4.1 allows an unauthorized user to create an admin user via the …

CVE-2024-24592 9.8

Lack of authentication in all versions of the fileserver component of Allegro AI’s ClearML platform allows a remote attacker to …

CVE-2026-8205