CVE-2024-7885 is a concurrency vulnerability classified as a race condition in the Undertow web server, specifically within the ProxyProtocolReadListener class. The root cause is the reuse of a single StringBuilder instance across multiple HTTP requests processed on the same connection. The parseProxyProtocolV1 method, responsible for handling the Proxy Protocol v1 headers, does not properly synchronize access to this shared StringBuilder. Consequently, simultaneous requests can overwrite or mix data within this buffer, leading to potential leakage of information between requests or responses. This can manifest as erroneous reuse of data from a previous request, causing unintended exposure of sensitive information. The vulnerability primarily causes errors and connection terminations, impacting availability, but the data leakage risk affects confidentiality as well. The affected versions include Undertow 0 through 2.3.0.Alpha1. The CVSS v3.1 base score is 7.5 (high), reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and an impact mainly on availability. No known exploits are reported yet, but the flaw is exploitable remotely without authentication. Undertow is widely used as a Java web server and servlet container, often embedded in middleware and application servers, making this vulnerability relevant to many enterprise environments.

For European organizations, the impact of CVE-2024-7885 can be significant, especially for those relying on Undertow as part of their web infrastructure or embedded in middleware stacks. The vulnerability can lead to service disruptions due to connection errors and terminations, affecting availability and potentially causing denial of service conditions. More critically, the risk of data leakage between HTTP requests on the same connection could expose sensitive information such as authentication tokens, session identifiers, or private data, violating data protection regulations like GDPR. This could result in reputational damage, regulatory fines, and loss of customer trust. Organizations operating multi-tenant environments or handling sensitive user data over persistent HTTP connections are particularly vulnerable. The ease of exploitation without authentication increases the threat level, especially for internet-facing services. Additionally, the concurrency nature of the flaw complicates detection and mitigation, potentially allowing attackers to extract data intermittently.

To mitigate CVE-2024-7885, European organizations should immediately upgrade Undertow to a patched version once available, as the vulnerability affects all versions up to 2.3.0.Alpha1. In the absence of an official patch, organizations can implement the following specific mitigations: 1) Disable or avoid using the Proxy Protocol feature if not strictly necessary, reducing exposure to the vulnerable code path. 2) Configure HTTP connections to avoid persistent multi-request reuse where possible, limiting concurrent access to shared resources. 3) Employ network-level controls such as Web Application Firewalls (WAFs) to detect and block suspicious request patterns that might exploit concurrency issues. 4) Conduct thorough code reviews and testing if Undertow is embedded in custom applications, ensuring no unsafe reuse of mutable objects across threads. 5) Monitor logs for unusual connection errors or data anomalies that could indicate exploitation attempts. 6) Isolate critical services behind reverse proxies or load balancers that do not use the vulnerable Proxy Protocol implementation. These targeted steps go beyond generic advice by focusing on the specific concurrency and Proxy Protocol aspects of the vulnerability.