CVE-2025-27136 LocalS3 CreateBucketConfiguration Endpoint XML External Entity (XXE) Injection
An attacker can exploit XXE in LocalS3 to perform SSRF and read internal data by sending crafted XML during bucket creation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-27136?
CVE-2025-27136 is a medium-severity vulnerability in Robothy local-s3, published on 10 Mar 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
LocalS3 is an Amazon S3 mock service for testing and local development. Prior to version 1.21, the LocalS3 service's bucket creation endpoint is vulnerable to XML External Entity (XXE) injection. When processing the CreateBucketConfiguration XML document during bucket creation, the service's XML parser is configured to resolve external entities. This allows an attacker to declare an external entity that references an internal URL, which the server will then attempt to fetch when parsing the XML. The vulnerability specifically occurs in the location constraint processing, where the XML parser resolves external entities without proper validation or restrictions. When the external entity is resolved, the server makes an HTTP request to the specified URL and includes the response content in the parsed XML document. This vulnerability can be exploited to perform server-side request forgery (SSRF) attacks, allowing an attacker to make requests to internal services or resources that should not be accessible from external networks. The server will include the responses from these internal requests in the resulting bucket configuration, effectively leaking sensitive information. The attacker only needs to be able to send HTTP requests to the LocalS3 service to exploit this vulnerability.
Weakness: CWE-611
Which versions are affected by CVE-2025-27136?
2 open source packages ship an affected version, including io.github.robothy:local-s3-rest.
| Package | Affected | Fixed in |
|---|---|---|
io.github.robothy:local-s3-rest Maven | All versions | 1.21 |
io.github.robothy:local-s3-rest Maven | All versions | 1.21 |
How do I fix CVE-2025-27136?
Upgrade io.github.robothy:local-s3-rest to 1.21 or later.
Is CVE-2025-27136 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-27136 exists.
Public exploit code: 2 proofs of concept on GitHub.
Sources
Also known as GHSA-g6wm-2v64-wq36.