CVE-2022-43690 is a medium-severity vulnerability affecting Concrete CMS versions below 8.5.10 and between 9.0.0 and 9.1.2. The issue arises from the improper use of non-strict comparison when validating the legacy_salt value during authentication processes. Specifically, the system uses loose comparison operators instead of strict ones, which can lead to a limited authentication bypass. This means an attacker could potentially bypass certain authentication checks by exploiting type juggling or similar weaknesses in the comparison logic. The vulnerability is classified under CWE-287, which relates to improper authentication. Exploitation requires user interaction (UI:R) but no privileges (PR:N) and can be performed remotely over the network (AV:N) with low attack complexity (AC:L). The impact includes limited confidentiality, integrity, and availability loss, as indicated by the CVSS vector (C:L/I:L/A:L). The vulnerability does not have known exploits in the wild as of the publication date. Remediation involves upgrading Concrete CMS to versions 8.5.10 or 9.1.3 and above, where strict comparison is enforced for the legacy_salt check, effectively mitigating the authentication bypass risk. Concrete CMS is a popular open-source content management system used for building websites and web applications, often deployed by organizations for managing digital content and web presence.

For European organizations using Concrete CMS within the affected version ranges, this vulnerability poses a moderate risk. An attacker exploiting this flaw could bypass authentication mechanisms partially, potentially gaining unauthorized access to restricted areas or functionalities within the CMS. This could lead to unauthorized content modifications, data leakage, or further pivoting within the network if the CMS is integrated with other internal systems. The limited scope of the bypass and the requirement for user interaction reduce the likelihood of widespread automated exploitation. However, organizations with public-facing Concrete CMS installations, especially those managing sensitive or regulated data (e.g., government portals, financial institutions, healthcare providers), could face reputational damage, compliance violations, and operational disruptions if exploited. The vulnerability may also be leveraged as a stepping stone for more complex attacks if combined with other vulnerabilities or misconfigurations.

1. Immediate upgrade to Concrete CMS version 8.5.10 or 9.1.3 and above to ensure the strict comparison fix is applied. 2. Conduct an audit of all Concrete CMS instances within the organization to identify any running vulnerable versions. 3. Implement web application firewalls (WAFs) with rules tailored to detect and block suspicious authentication bypass attempts targeting Concrete CMS legacy_salt parameters. 4. Enforce multi-factor authentication (MFA) on CMS administrative accounts to reduce the risk of unauthorized access even if authentication bypass attempts occur. 5. Monitor CMS logs for unusual authentication patterns or repeated failed login attempts that might indicate exploitation attempts. 6. Restrict access to the CMS backend by IP whitelisting or VPN-only access where feasible, limiting exposure to potential attackers. 7. Educate administrators and developers about the importance of strict type comparisons in authentication logic to prevent similar issues in custom code or plugins. 8. Regularly review and update CMS plugins and extensions to ensure compatibility with patched CMS versions and avoid introducing new vulnerabilities.