CVE-2026-17615
Description
A flaw was found in RESTEasy's SourceProvider. This vulnerability allows an unauthenticated attacker to perform an unauthenticated remote file read. By sending a specially crafted XML body with a DOCTYPE declaration referencing external entities to an endpoint that accepts application/xml and returns Source or StreamSource, the server can be tricked into resolving the entity and including sensitive file contents in the HTTP response. This is due to the SourceProvider.writeTo() method creating a SAXParser without disabling external entity resolution, leading to an XML External Entity (XXE) vulnerability.
Statement
Important: This flaw allows unauthenticated remote file disclosure due to improper XML external entity (XXE) resolution in RESTEasy's SourceProvider. An attacker can exploit this by sending a crafted XML request to an exposed endpoint that processes application/xml and returns Source or StreamSource types, leading to the disclosure of sensitive server-side files. This affects applications utilizing RESTEasy where endpoints are configured to accept XML input and return Source or StreamSource objects, potentially exposing sensitive data on Red Hat supported products.
Mitigation
To mitigate this issue, avoid exposing RESTEasy endpoints that return Source or StreamSource types. Alternatively, implement a custom MessageBodyWriter for Source types that explicitly applies XML security features to the SAXParserFactory before parsing. Changes to application configuration or code typically require an application redeployment or restart to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data; Read Files or Directories
If the attacker is able to include a crafted DTD and a default entity resolver is enabled, the attacker may be able to access arbitrary files on the system. By submitting an XML file that defines an external entity with a file:// URI, an attacker can cause the processing application to read the contents of a local file. For example, a URI such as "file:///c:/winnt/win.ini" designates (in Windows) the file C:\Winnt\win.ini, or file:///etc/passwd designates the password file in Unix-based systems. Once the content of the URI is read, it is fed back into the application that is processing the XML. This application may echo back the data (e.g., in an error message), thereby exposing the file contents.
Integrity
Technical Impact: Bypass Protection Mechanism
An attacker may supply a crafted DTD using URIs with schemes such as http://, forcing the application to make outgoing HTTP requests to servers that the attacker cannot reach directly, which can be used to bypass firewall restrictions; hide the source of attacks such as port scanning; or otherwise leverage the server's trust relationship with other entities.
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
The product could consume excessive CPU cycles or memory using a URI that points to a large file, or a device that always returns data such as /dev/random. Alternately, the URI could reference a file that contains many nested or recursive entity references to further slow down parsing.
Acknowledgements
Red Hat would like to thank Leon Zlobecki for reporting this issue.
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