# CVE-2026-59354: Spring Security OAuth2 Authorization Server metadata validation in Dynamic Client Registration

Source: https://junglewise.ai/threats/cve-2026-59354-spring-security-oauth2-authorization-server-metadata-validation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-27. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-59354 · Severity: critical · CVSS 9.6 · Published 2026-08-27

Spring Security's OAuth2 Authorization Server module is used to implement OAuth2 authorization for applications. When Dynamic Client Registration is enabled, the registration endpoint fails to properly validate client-supplied metadata, allowing an attacker with a valid Initial Access Token to register a malicious client. This can lead to stored cross-site scripting, privilege escalation, or server-side request forgery attacks depending on how the metadata is used.

Technologies: [VMware Spring Security](https://junglewise.ai/threats/technologies/spring-security). Vendors: [VMware](https://junglewise.ai/threats/vendors/vmware).

## Quick answers

**Is CVE-2026-59354 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59354 being exploited in the wild.

**How severe is CVE-2026-59354?** Critical severity, with a CVSS score of 9.6, published 27 August 2026.

**Which products and versions are affected?** VMware Spring Security OAuth2 Authorization Server 7.0.0 through 7.0.4.

**Is there a fix for CVE-2026-59354?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-59354 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-59354?** Check whether you run VMware Spring Security or VMware Spring Security OAuth2 Authorization Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This vulnerability is an input validation flaw in the Dynamic Client Registration endpoint of Spring Security's OAuth2 Authorization Server (versions 7.0.0 through 7.0.4). The registration endpoint accepts and stores client metadata without sufficient validation, allowing an attacker who possesses a valid Initial Access Token to craft malicious metadata fields. Depending on server configuration and how the metadata is rendered or used downstream, this can result in Stored Cross-Site Scripting (XSS), Privilege Escalation, or Server-Side Request Forgery (SSRF) attacks. The vulnerability requires authentication (possession of a valid Initial Access Token) but is network-reachable. Patches are available in versions 7.0.5 and later.

## Affected products

- VMware Spring Security OAuth2 Authorization Server 7.0.0 through 7.0.4

## Timeline

- 2026-08-27: disclosed

## References

- [https://repo.maven.apache.org/maven2/org/springframework/security/spring-security-oauth2-authorization-server/](https://repo.maven.apache.org/maven2/org/springframework/security/spring-security-oauth2-authorization-server/)

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