CVE-2025-11273 identifies a deserialization vulnerability in LaChatterie Verger, a software product used up to version 1.2.10. The flaw exists in the redirectToAuthorization function located in /src/main/services/mcp/oauth/provider.ts, where the URL argument is improperly handled, leading to unsafe deserialization. Deserialization vulnerabilities occur when untrusted data is parsed into objects without sufficient validation, enabling attackers to craft malicious payloads that can execute arbitrary code or manipulate application state. This vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The CVSS 4.0 score of 5.3 reflects a medium severity, indicating limited but meaningful impact on confidentiality, integrity, and availability. The vendor was notified early but has not issued patches or advisories, and no official patch links are available. Although no active exploits have been observed in the wild, the public disclosure of exploit code raises the likelihood of future attacks. The vulnerability affects all versions from 1.2.0 through 1.2.10, necessitating urgent attention from users of these versions. The attack vector targets OAuth authorization flows, which are critical for secure authentication and authorization in many enterprise environments. Exploitation could allow attackers to bypass security controls, manipulate authorization redirects, or execute arbitrary code within the application context, potentially compromising sensitive data or disrupting service availability.

For European organizations, the impact of CVE-2025-11273 can be significant, especially for those relying on LaChatterie Verger in their OAuth authorization infrastructure. Successful exploitation could lead to unauthorized access, data leakage, or service disruption, undermining trust in authentication mechanisms. This is particularly concerning for sectors with strict data protection requirements such as finance, healthcare, and government, where confidentiality and integrity are paramount. The vulnerability’s remote exploitability without authentication means attackers can target exposed services directly, increasing risk to internet-facing systems. Additionally, the lack of vendor response and patches prolongs exposure, forcing organizations to implement compensating controls. Disruption of OAuth flows could impact user access and business continuity. The medium severity rating suggests that while the vulnerability is not critical, it still poses a tangible threat that could be leveraged as part of a broader attack chain. Organizations with complex OAuth integrations or those using LaChatterie Verger in multi-tenant environments face elevated risks of lateral movement or privilege escalation.

Given the absence of official patches, European organizations should implement the following mitigations: 1) Apply strict input validation and sanitization on all URL parameters passed to the redirectToAuthorization function to prevent malicious payloads from triggering deserialization. 2) Employ application-layer controls to restrict or disable unsafe deserialization mechanisms if configurable. 3) Use web application firewalls (WAFs) with custom rules to detect and block suspicious deserialization payloads targeting the vulnerable endpoint. 4) Limit network exposure by restricting access to the affected service to trusted IP ranges or via VPN. 5) Monitor logs and network traffic for anomalous activity indicative of exploitation attempts, such as unusual OAuth redirect requests or malformed URL parameters. 6) Consider deploying runtime application self-protection (RASP) tools to detect and block deserialization attacks in real time. 7) Engage with LaChatterie vendor support channels to seek updates or patches and track vulnerability advisories. 8) Plan for an upgrade or migration away from affected versions as soon as a patch or secure version becomes available. 9) Conduct security reviews of OAuth implementations to ensure best practices and minimize attack surface. 10) Educate development teams about secure deserialization practices to prevent similar vulnerabilities in future releases.