Spring Cloud Function CVE-2026-59299

Exploitation requires all three of the following simultaneously: (1) the Spring Cloud Function deployment must have function composition enabled and the composition lookup feature active - deployments using only simple, non-composed functions are not exposed; (2) the attacker must already hold high privileges (PR:H), meaning operator-level or equivalent access to define or influence composition lookups - a fully unauthenticated or low-privilege attacker cannot trigger the vulnerability; (3) user interaction is required (UI:R), meaning a victim must actively trigger the composed function invocation. What limits exploitation beyond the CVSS floor: the combination of PR:H and UI:R means that even a fully network-accessible deployment is protected by both an authentication barrier and a social engineering dependency. Organizations where function composition management is restricted to a small, trusted set of administrators face minimal realistic risk.

Overall risk is low. The vendor CVSS score of 3.1 (AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N) reflects a tightly constrained attack: the adversary must hold high privileges, navigate a high-complexity path, and depend on user interaction - any one of these conditions independently reduces the viable attack population significantly. No EPSS score was available in the input data. The vulnerability is absent from the CISA KEV catalog and no public proof-of-concept has been identified. Impact is bounded to limited confidentiality and integrity degradation with no availability consequence. This is unlikely to represent an immediate triage priority for most organizations; however, Spring Cloud Function deployments that expose composition management to partially-trusted operators with heterogeneous function pipelines should treat this as a meaningful integrity concern warranting patching on a normal patch cycle.

A highly privileged operator - such as a user with access to function deployment or composition configuration in a Spring Cloud Function environment - crafts a malicious composition lookup targeting the base function. When a victim user triggers the composed function invocation, the crafted lookup poisons the base function's state, potentially leaking limited configuration or processing data or subtly altering function output. No public proof-of-concept exploit is known at time of analysis.