Description

Potential for improper filtering of HTTP headers in Spring Cloud Function. Spring Cloud Function 5.0.0 - 5.0.3 Spring Cloud Function 4.3.0 - 4.3.4 Spring Cloud Function 4.2.0 - 4.2.7 Spring Cloud Function 3.2.16 and earlier

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "3.1",
  "pubDate": "2026-08-27T20:17:56.060Z",
  "pubdate": "2026-08-27T20:17:56.060Z",
  "executiveSummary": "This vulnerability involves improper filtering of HTTP headers within the Spring Cloud Function framework, leading to a potential security risk related to header injection.\nThe flaw allows unauthorized manipulation of request headers, which can facilitate various downstream attacks such as request smuggling, cache poisoning, or bypassing security controls that rely on header-based authentication or filtering.\nAffected products include Spring Cloud Function versions 5.0.0 through 5.0.3, 4.3.0 through 4.3.4, 4.2.0 through 4.2.7, and 3.2.16 and earlier.\nThe vulnerability poses significant risk in cloud-native environments where function routing and processing depend heavily on HTTP metadata.\nExploitation generally requires an attacker to possess the ability to craft and transmit malicious HTTP requests to the application endpoint.\nSuccessful exploitation may lead to unauthorized access, integrity compromise, or security bypasses, depending on how the application utilizes the tainted headers.",
  "technicalDetails": "The vulnerability stems from insufficient sanitization and validation of HTTP headers processed by Spring Cloud Function. When the framework handles incoming requests, it maps specific HTTP header values to internal processing structures or routes functions based on these values without adequate input filtering.\nThe root cause is identified as an improper trust boundary definition where user-supplied HTTP headers are parsed and interpreted by the framework's routing logic or functional invocation components without sanitizing characters that may trigger header injection or smuggling behaviors.\nThe exploitation flow typically begins when an attacker sends a crafted HTTP request containing malicious headers. If the underlying infrastructure or the application logic treats these header values as trusted metadata for downstream processing, the injection occurs.\nFor example, if an application relies on a custom header for routing, an attacker might inject control characters or duplicate headers that deviate from expected standard protocol behavior. If the application server or the Spring Cloud Function component fails to normalize these headers, the injected values could be utilized to manipulate the application's internal state.\nIn the context of Spring Cloud Function, the vulnerability allows an attacker to influence the functional pipeline. By injecting headers that are later used in function invocation or routing, an attacker may force the framework to route requests to unintended functions or bypass security filters that validate requests based on header content.\nThe exposure is network-based; any interface that accepts HTTP requests for Spring Cloud Function processing is potentially vulnerable. The attack does not necessarily require high-privileged access if the endpoint is exposed publicly, and the impact is contingent on the downstream consumption of the headers within the application logic.\nOnce the initial injection is successful, the post-exploitation impact includes the potential for Cross-Site Scripting (XSS) if the headers are reflected in responses, cache poisoning by manipulating headers used for caching keys, or the redirection of traffic to sensitive internal functions that were not intended to be publicly reachable.\nBecause Spring Cloud Function is designed to act as a bridge between HTTP requests and functional logic, the framework acts as a critical intermediary. If this intermediary fails to enforce header integrity, it effectively extends the attack surface to any downstream service that consumes the tainted request context.\nThis behavior affects a broad range of versions: 5.0.0-5.0.3, 4.3.0-4.3.4, 4.2.0-4.2.7, and 3.2.16 and earlier, indicating a persistent architectural weakness in how incoming request metadata is handled prior to functional execution."
}