CVE-2025-7054 in quiche
Summary
by MITRE • 08/07/2025
Cloudflare quiche was discovered to be vulnerable to an infinite loop when sending packets containing RETIRE_CONNECTION_ID frames.
QUIC connections possess a set of connection identifiers (IDs); see Section 5.1 of RFC 9000 https://datatracker.ietf.org/doc/html/rfc9000#section-5.1 . Once the QUIC handshake completes, a local endpoint is responsible for issuing and retiring Connection IDs that are used by the remote peer to populate the Destination Connection ID field in packets sent from remote to local. Each Connection ID has a sequence number to ensure synchronization between peers.
An unauthenticated remote attacker can exploit this vulnerability by first completing a handshake and then sending a specially-crafted set of frames that trigger a connection ID retirement in the victim. When the victim attempts to send a packet containing RETIRE_CONNECTION_ID frames, Section 19.16 of RFC 9000 https://datatracker.ietf.org/doc/html/rfc9000#section-19.6 requires that the sequence number of the retired connection ID must not be the same as the sequence number of the connection ID used by the packet. In other words, a packet cannot contain a frame that retires itself. In scenarios such as path migration, it is possible for there to be multiple active paths with different active connection IDs that could be used to retire each other. The exploit triggered an unintentional behaviour of a quiche design feature that supports retirement across paths while maintaining full connection ID synchronization, leading to an infinite loop.This issue affects quiche: from 0.15.0 before 0.24.5.
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Analysis
by VulDB Data Team • 08/14/2025
The vulnerability identified as CVE-2025-7054 affects Cloudflare's quiche library, a rust implementation of the QUIC protocol that serves as a foundational component for many network applications. This flaw manifests as an infinite loop condition that occurs when processing packets containing RETIRE_CONNECTION_ID frames, representing a critical denial-of-service risk that can be exploited by unauthenticated remote attackers. The issue specifically targets the QUIC protocol's connection identifier management system as defined in RFC 9000, where connection IDs serve as unique identifiers for establishing and maintaining secure communication channels between endpoints. The vulnerability exploits the synchronization mechanisms that govern how connection IDs are issued, used, and retired during the lifecycle of QUIC connections.
The technical exploitation involves an attacker completing a standard QUIC handshake process before sending maliciously crafted frames designed to trigger connection ID retirement behavior. According to RFC 9000 Section 19.16, there exists a fundamental protocol constraint that prevents a packet from containing a frame that retires its own connection ID, as this would create logical inconsistencies in the connection state management. However, the quiche implementation contains a design feature that supports retirement across different network paths while maintaining full connection ID synchronization, which creates an unintended code path. When an attacker crafts packets that exploit this synchronization mechanism, the implementation enters a condition where it continuously processes retirement operations without proper termination, leading to the infinite loop behavior.
This vulnerability impacts systems using quiche versions from 0.15.0 through 0.24.4, affecting a substantial portion of applications that rely on Cloudflare's QUIC implementation for network communication. The operational impact represents a severe denial-of-service condition that can cause affected systems to consume excessive CPU resources, potentially leading to complete service unavailability. The infinite loop consumes system resources continuously without yielding control back to normal processing, effectively rendering the vulnerable application incapable of handling legitimate traffic. This behavior aligns with CWE-835, which categorizes infinite loops as a class of software vulnerabilities that can lead to system resource exhaustion and service disruption. The attack vector requires only a single malicious packet to trigger the condition, making it particularly dangerous as it can be executed with minimal resources and network overhead.
The exploitation mechanism demonstrates a complex interaction between protocol compliance and implementation design, where adherence to RFC specifications creates a scenario that conflicts with internal synchronization logic. This vulnerability represents a classic case of protocol feature abuse where legitimate functionality becomes exploitable due to implementation-specific design choices. Organizations using affected versions of quiche should prioritize immediate patching to address the infinite loop condition that can be triggered by remote unauthenticated attackers. The remediation strategy involves upgrading to quiche version 0.24.5 or later, which contains the necessary fixes to prevent the synchronization mechanism from entering the problematic infinite loop state. Security teams should also implement monitoring for unusual CPU usage patterns that may indicate exploitation attempts, as the vulnerability manifests through resource exhaustion rather than direct code execution. This issue highlights the importance of thorough testing for edge cases in protocol implementations, particularly around state management and synchronization mechanisms that operate under concurrent access conditions. The vulnerability's classification aligns with ATT&CK technique T1499.004, which covers network denial of service through resource exhaustion, and represents a significant risk to network availability and service integrity in systems relying on QUIC-based communication protocols.