CVE-2022-43660 is a high-severity vulnerability affecting multiple versions of Six Apart Ltd.'s Movable Type content management system (CMS), specifically Movable Type 7 r.5301 and earlier, Movable Type Advanced 7 r.5301 and earlier, Movable Type Premium 1.53 and earlier, and Movable Type Premium Advanced 1.53 and earlier. The vulnerability arises from improper neutralization of Server-Side Includes (SSI) within web pages, classified under CWE-94 (Improper Control of Generation of Code). This flaw allows a remote attacker who is authenticated and possesses the 'Manage of Content Types' privilege to execute arbitrary Perl scripts or operating system commands on the affected server. The attack vector requires no user interaction beyond authentication, and the vulnerability has a CVSS v3.1 base score of 7.2, indicating high severity. The vulnerability impacts confidentiality, integrity, and availability, as arbitrary code execution can lead to data theft, data manipulation, and service disruption. Although no known exploits have been reported in the wild, the ease of exploitation for a privileged user and the potential damage make this a critical concern for organizations using affected Movable Type versions. The vulnerability specifically targets the SSI processing mechanism within the CMS, which is used to embed dynamic content. Improper sanitization allows malicious input to be interpreted as executable code, thus compromising the server environment. Since the attack requires authenticated access with specific privileges, the risk is primarily to organizations with insufficient access controls or compromised privileged accounts. Movable Type is used primarily for website and blog management, often by enterprises, media companies, and organizations requiring robust content workflows.

For European organizations, this vulnerability poses significant risks, especially for those relying on Movable Type CMS for managing corporate websites, intranets, or customer-facing portals. Successful exploitation can lead to full system compromise, enabling attackers to steal sensitive data, alter website content, deploy malware, or disrupt services. This can damage organizational reputation, lead to regulatory non-compliance (e.g., GDPR breaches due to data exposure), and cause operational downtime. Given that the vulnerability requires privileged authenticated access, the impact is heightened in environments with weak internal access controls or where credential theft is prevalent. Additionally, organizations in sectors such as media, government, and finance, which often use CMS platforms extensively, may face targeted attacks aiming to manipulate public information or conduct espionage. The ability to execute arbitrary OS commands also opens the door for lateral movement within networks, increasing the scope of potential damage. Since no public exploits are currently known, proactive patching and mitigation are critical to prevent future exploitation attempts.

1. Immediate patching: Organizations should upgrade to the latest versions of Movable Type where this vulnerability is fixed. If patches are not yet available, consider applying vendor-provided workarounds or disabling SSI processing features if feasible. 2. Privilege review: Restrict the 'Manage of Content Types' privilege strictly to trusted administrators. Implement the principle of least privilege to minimize the number of users who can exploit this vulnerability. 3. Access controls: Enforce strong authentication mechanisms such as multi-factor authentication (MFA) for all privileged accounts to reduce the risk of credential compromise. 4. Input validation: Where possible, implement additional input sanitization or filtering at the web application firewall (WAF) level to detect and block suspicious SSI payloads. 5. Monitoring and logging: Enable detailed logging of CMS administrative actions and monitor for unusual activities, such as unexpected Perl script executions or OS command invocations. 6. Network segmentation: Isolate CMS servers from critical internal systems to limit lateral movement if compromise occurs. 7. Incident response readiness: Prepare and test incident response plans specifically addressing CMS compromise scenarios. 8. Vendor communication: Maintain active communication with Six Apart Ltd. for updates, patches, and advisories related to this vulnerability.