CVE-2024-42487 in Cilium
Summary
by MITRE • 08/16/2024
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. In the 1.15 branch prior to 1.15.8 and the 1.16 branch prior to 1.16.1, Gateway API HTTPRoutes and GRPCRoutes do not follow the match precedence specified in the Gateway API specification. In particular, request headers are matched before request methods, when the specification describes that the request methods must be respected before headers are matched. This could result in unexpected behaviour with security This issue is fixed in Cilium v1.15.8 and v1.16.1. There is no workaround for this issue.
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Analysis
by VulDB Data Team • 09/30/2024
The vulnerability identified as CVE-2024-42487 affects Cilium versions prior to 1.15.8 and 1.16.1, specifically within the Gateway API implementation that governs HTTPRoutes and GRPCRoutes. This security flaw represents a critical deviation from the established Gateway API specification, which defines precise match precedence rules for route matching operations. The issue manifests in how Cilium processes incoming requests when evaluating match conditions, creating a scenario where header-based matching occurs before method-based matching, directly contradicting the standard specification requirements.
The technical flaw stems from improper implementation of the Gateway API match precedence logic within Cilium's eBPF-based data plane. According to the Gateway API specification, when multiple match conditions are present in a route definition, request methods should take precedence over header matching to ensure predictable routing behavior. However, the vulnerable Cilium versions execute header matching first, which can lead to unintended route selection and potentially compromise security controls. This misordering creates a path where malicious requests could bypass intended security policies by exploiting the incorrect match evaluation order, particularly when security policies rely on specific method matching before header validation.
The operational impact of this vulnerability extends beyond simple routing anomalies to encompass potential security implications within network policy enforcement. When security policies depend on method-based routing controls, the incorrect match precedence could allow unauthorized access patterns or bypass established security boundaries. Attackers could potentially exploit this behavior to route traffic through unintended paths or to circumvent access controls that rely on proper method matching before header validation. This vulnerability affects the integrity of network security policies and could undermine the trustworthiness of Cilium's Gateway API implementation in enforcing security controls.
This vulnerability maps directly to CWE-1214, which addresses improper handling of match precedence in API routing implementations, and aligns with ATT&CK technique T1071.004 for application layer protocol manipulation. The lack of a workaround means that organizations must upgrade to the patched versions to remediate the issue, as there is no alternative configuration or code modification that can safely address the root cause without potentially introducing additional security risks. The fix implemented in Cilium v1.15.8 and v1.16.1 ensures proper adherence to the Gateway API specification by correcting the match precedence order to respect method matching before header matching. Organizations should prioritize upgrading their Cilium deployments to eliminate this security gap and maintain compliance with established API specification standards.