CVE-2025-11273 is a medium severity vulnerability affecting LaChatterie Verger versions 1.2.0 through 1.2.10. The flaw exists in the redirectToAuthorization function located in the /src/main/services/mcp/oauth/provider.ts file. Specifically, the vulnerability arises from improper handling of the URL argument, which leads to unsafe deserialization. Deserialization vulnerabilities occur when untrusted input is deserialized without sufficient validation or sanitization, potentially allowing an attacker to execute arbitrary code or manipulate application logic remotely. In this case, the vulnerability can be exploited remotely without requiring user interaction or authentication, increasing the attack surface. Although the CVSS 4.0 base score is 5.3 (medium), the exploitability is notable because the attack vector is network-based with low attack complexity and no privileges or user interaction needed. The vendor was notified early but has not responded or issued a patch, and no official patch links are available. Public exploit code has been released, raising the risk of exploitation despite no known active exploitation in the wild at the time of publication. The vulnerability impacts confidentiality, integrity, and availability to a limited extent due to the low impact metrics in the CVSS vector, but the remote code execution potential inherent in deserialization flaws warrants caution. The lack of vendor response and public exploit availability increases urgency for affected organizations to implement mitigations or consider alternative controls.

For European organizations using LaChatterie Verger versions 1.2.0 to 1.2.10, this vulnerability poses a tangible risk of remote compromise. Exploitation could allow attackers to execute arbitrary code or manipulate authorization flows, potentially leading to unauthorized access or disruption of services. This is particularly concerning for organizations relying on Verger for OAuth authorization services, as compromise could cascade to other connected systems or sensitive data. The medium severity rating reflects moderate impact, but the ease of remote exploitation without authentication increases risk. Organizations in sectors with stringent data protection requirements (e.g., finance, healthcare, government) could face regulatory and reputational damage if exploited. The absence of a vendor patch means organizations must rely on compensating controls, increasing operational burden. The vulnerability could also be leveraged in targeted attacks or supply chain compromises, especially given the public availability of exploit code. Overall, the threat could disrupt business continuity and data confidentiality for European entities using this software.

Given the lack of an official patch, European organizations should implement the following specific mitigations: 1) Immediately audit all instances of LaChatterie Verger to identify affected versions and isolate or restrict network access to these systems, especially limiting inbound traffic to trusted sources. 2) Employ Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with custom rules to detect and block suspicious deserialization payloads or anomalous URL parameters targeting the redirectToAuthorization function. 3) Conduct code reviews or implement runtime application self-protection (RASP) to detect and prevent unsafe deserialization attempts within the application. 4) Where feasible, upgrade to a newer, unaffected version of Verger once available or consider alternative OAuth providers with active security support. 5) Monitor logs and network traffic closely for exploitation attempts, focusing on unusual authorization redirects or malformed URL parameters. 6) Implement strict input validation and sanitization on URL parameters at the application or proxy level to prevent malicious payloads from reaching the vulnerable code. 7) Prepare incident response plans tailored to potential exploitation scenarios involving OAuth authorization bypass or remote code execution. These targeted actions go beyond generic advice and address the specific nature of this deserialization vulnerability.