---
id: "CVE-2026-59396"
kind: "vulnerability"
aliases: ["CVE-2026-59396"]
title: "UAA: private_key_jwt login flaw lets anonymous requests exhaust server memory"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["cloud-foundry", "infrastructure", "java", "private-key-jwt", "self-hosted", "uaa"]
not_affected_if: ["managed-hosting", "no-private-key-jwt", "no-remote-jwks"]
published_at: "2026-10-30T09:17:15+00:00"
first_seen_at: "2026-10-30T09:29:39+00:00"
updated_at: "2026-10-30T09:30:36+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59396", "first_seen_at": "2026-10-30T09:29:39+00:00"}]
---

# UAA: private_key_jwt login flaw lets anonymous requests exhaust server memory

UAA, the Cloud Foundry identity service, caches remote JWKS responses used for private_key_jwt client authentication. Invalid login attempts can force repeated parsing of these large cached objects, burning CPU and possibly causing Java out-of-memory errors that take the service down.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether the deployment uses private_key_jwt client authentication with a remote JWKS URI on clients.
- Check the UAA version in use against the fixed versions listed by the vendor: unknown from the sources.

## Timeline

- 2026-10-30T09:29:39+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-59396

## From the sources

A denial-of-service vulnerability exists in UAA's private_key_jwt client-authentication mechanism. When UAA retrieves a remote JWKS URI, it caches the response. Invalid authentication attempts can trigger full deserialization of this cached data. An attacker with prerequisites (write access to clients or a compromised endpoint) can send anonymous requests that force repeated parsing of large cached objects, causing excessive CPU usage and potential Java heap exhaustion via OutOfMemoryError, resulting in service unavailability.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_