CVE-2026-45609 is a high-severity (CVSS 7.2) Server-Side Request Forgery (SSRF) vulnerability in org.springaicommunity:mcp-client-security. A fix is available for org.springaicommunity:mcp-client-security — see the affected versions and patch details below.
mcp-security: Unvalidated URL Fetching (SSRF)
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45609.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.springaicommunity:mcp-client-securityReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The mcp-security framework fails to implement the mandatory SSRF mitigations outlined in the Model Context Protocol (MCP) security specifications. Specifically, it processes untrusted URLs for OAuth-related discovery and metadata without verifying if the targets are malicious or internal to the network.
This only affects installations with Dynamic Client Registration (DCR) enabled:
spring.ai.mcp.client.authorization.dynamic-client-registration.enabled=true
DCR does not validate URLs exposed by MCP Servers (protected resource metadata URL, authorization server URL) and Authorization Servers (all OAuth2 endpoints).
Workaround
When users need to perform DCR, they may provide their own McpOAuth2ClientManager. Both McpMetadataDiscoveryService and DynamicClientRegistrationService are also affected, if used, users should provide their own subclasses.
Alternatively, users can provide the default implementations of these classes with a RestClient that implements URL filtering through ClientHttpRequestInterceptor.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.springaicommunity:mcp-client-security | all versions | 0.1.9org.springaicommunity:mcp-client-security:0.1.9 |
Affected Products
mcp securityspringaicommunityDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.springaicommunity:mcp-client-security, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.springaicommunity:mcp-client-security to 0.1.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45609 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
Frequently Asked Questions
Is CVE-2026-45609 in your dependencies?
Find it across Maven, including transitive dependencies.