CVE-2024-36401

GeoServer is an open source server that allows users to share and edit geospatial data. Prior to versions 2.23.6, 2.24.4, and 2.25.2, multiple OGC request parameters allow Remote Code Execution (RCE) by unauthenticated users through specially crafted input against a default GeoServer installation due to unsafely evaluating property names as XPath expressions.

The GeoTools library API that GeoServer calls evaluates property/attribute names for feature types in a way that unsafely passes them to the commons-jxpath library which can execute arbitrary code when evaluating XPath expressions. This XPath evaluation is intended to be used only by complex feature types (i.e., Application Schema data stores) but is incorrectly being applied to simple feature types as well which makes this vulnerability apply to ALL GeoServer instances. No public PoC is provided but this vulnerability has been confirmed to be exploitable through WFS GetFeature, WFS GetPropertyValue, WMS GetMap, WMS GetFeatureInfo, WMS GetLegendGraphic and WPS Execute requests. This vulnerability can lead to executing arbitrary code.

Versions 2.23.6, 2.24.4, and 2.25.2 contain a patch for the issue. A workaround exists by removing the gt-complex-x.y.jar file from the GeoServer where x.y is the GeoTools version (e.g., gt-complex-31.1.jar if running GeoServer 2.25.1). This will remove the vulnerable code from GeoServer but may break some GeoServer functionality or prevent GeoServer from deploying if the gt-complex module is needed.

Weakness

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before using the input in a dynamic evaluation call (e.g. “eval”).

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• Inputs should be decoded and canonicalized to the application’s current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control.
• Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/35.html

References

• https://github.com/Warxim/CVE-2022-41852?tab=readme-ov-file#workaround-for-cve-2022-41852
• https://github.com/geoserver/geoserver/security/advisories/GHSA-6jj6-gm7p-fcvv
• https://github.com/geotools/geotools/pull/4797
• https://github.com/geotools/geotools/security/advisories/GHSA-w3pj-wh35-fq8w
• https://osgeo-org.atlassian.net/browse/GEOT-7587
• https://github.com/Warxim/CVE-2022-41852?tab=readme-ov-file#workaround-for-cve-2022-41852
• https://github.com/geoserver/geoserver/security/advisories/GHSA-6jj6-gm7p-fcvv
• https://github.com/geotools/geotools/pull/4797
• https://github.com/geotools/geotools/security/advisories/GHSA-w3pj-wh35-fq8w
• https://osgeo-org.atlassian.net/browse/GEOT-7587
• https://www.vicarius.io/vsociety/posts/geoserver-rce-cve-2024-36401