CVE-2025-7054 is a high-severity vulnerability affecting Cloudflare's quiche library, a widely used implementation of the QUIC protocol. The vulnerability arises from an infinite loop triggered when processing RETIRE_CONNECTION_ID frames in QUIC packets. QUIC connections use connection IDs with sequence numbers to manage multiple paths and maintain synchronization between peers. According to RFC 9000, a packet cannot retire the connection ID it uses, ensuring proper synchronization. However, quiche's design feature that supports connection ID retirement across multiple active paths inadvertently leads to an infinite loop when a specially crafted set of RETIRE_CONNECTION_ID frames is sent by an unauthenticated remote attacker after completing the handshake. This infinite loop can cause the affected quiche instance to hang or become unresponsive, resulting in a denial of service (DoS). The vulnerability affects quiche versions from 0.15.0 up to but not including 0.24.5. The CVSS 4.0 score is 8.7 (high), reflecting that the vulnerability is remotely exploitable without authentication or user interaction, and can cause significant availability impact. No known exploits are currently reported in the wild. The issue stems from a logic flaw in handling connection ID retirement across multiple paths, violating the protocol requirement that a packet must not retire the connection ID it uses, leading to an infinite loop in the packet processing logic.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Cloudflare's quiche library in their infrastructure or services implementing QUIC. The infinite loop can cause service outages or degraded performance due to resource exhaustion, effectively resulting in denial of service. This can disrupt web services, APIs, or any applications leveraging QUIC for transport, impacting availability and potentially causing operational downtime. Given the increasing adoption of QUIC for performance and security benefits, organizations using quiche-based implementations may face service interruptions, affecting customer experience and business continuity. Additionally, since the exploit requires no authentication or user interaction, attackers can remotely target vulnerable endpoints, increasing the risk of widespread disruption. The confidentiality and integrity of data are not directly impacted, but the availability degradation can have cascading effects on dependent systems and services.

To mitigate this vulnerability, European organizations should prioritize upgrading quiche to version 0.24.5 or later, where the infinite loop issue has been addressed. If immediate upgrade is not feasible, organizations should implement network-level protections such as rate limiting and filtering of suspicious QUIC packets containing RETIRE_CONNECTION_ID frames to reduce the risk of exploitation. Monitoring QUIC traffic for anomalies related to connection ID retirement frames can help detect potential exploitation attempts. Additionally, deploying application-layer DoS protection mechanisms and ensuring redundancy in services using quiche can minimize impact. Organizations should also review their QUIC implementation configurations to disable or restrict multi-path connection ID retirement features if possible until patched. Coordinating with Cloudflare or vendors using quiche for timely updates and patches is critical. Finally, incorporating this vulnerability into incident response plans and conducting tabletop exercises can prepare teams for potential exploitation scenarios.