Apache FreeMarker security advisories
Security information for Apache FreeMarker
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A malformed locale may be exploitable for path traversal attacks
CVE-2026-84939 [CVE] [CVE json] [OSV json]
Last updated: 2026-10-06T06:41:52.487Z
Affected
- Apache FreeMarker from 2.2.0 through 2.3.34
- Apache FreeMarker from 2.2.0 through 2.3.34
Description
Path traversal vulnerability in Apache FreeMarker template loading mechanism, if the attacker can specify an arbitrary malformed locale identifier to FreeMarker, and the localized lookup configuration setting is enabled (it’s by default enabled).
This issue affects Apache FreeMarker from 2.2.0 through 2.3.34.
Users are recommended to upgrade to version 2.3.35. Disabling localized lookup in previous versions also mitigates this.
Note that even in versions affected by this vulnerability, the files that can be loaded remain restricted by the TemplateLoader that FreeMarker is configured to use. In particular, FileTemplateLoader prevents attempts to traverse outside the baseDir specified in its constructor. Other TemplateLoader implementations may allow access outside their designated base directory, but they are still constrained by the underlying storage mechanism—for example, a loader wrapping a Java class loader can only access resources that the class loader can load, while one wrapping a web application context can only access resources available through that context.