Apache Tika CVE-2026-66756

The target must be running Apache Tika tika-server version 4.0.0-alpha-1 specifically - the only affected release. The vulnerability is meaningful only when enableUnsecureFeatures=false is configured (or left at its default disabled state), because the bypass only matters when the operator intended to restrict the endpoint. Tika-server exposes a plain HTTP REST interface with no built-in authentication mechanism, so any attacker who can reach the server on the network - even without credentials - can send requests to the /unpack endpoint. Exploitation requires no user interaction and no elevated privileges beyond network reachability. The primary limiting factor is the alpha pre-release nature of the affected version, which should not be present in any production environment.

No CVSS score or vector is provided in the source data, so all risk metrics below are independently assessed. No EPSS score is available and the CVE is not listed in the CISA KEV catalog, meaning active exploitation is unconfirmed. The most significant risk-limiting factor is that the affected version, 4.0.0-alpha-1, is explicitly pre-production alpha software not recommended for production deployment; real-world exposure should therefore be minimal. The tika-server REST interface generally lacks built-in authentication and relies on network-layer access controls for isolation, meaning any network-reachable alpha instance is exposed without additional prerequisites. The bypass enables access to the /unpack endpoint regardless of operator intent, but the practical impact depends on what an attacker can extract or process through that endpoint. Zip-bomb resource exhaustion and malicious archive parsing are the most plausible abuse paths. EPSS data is absent and KEV status is negative, consistent with a low-urgency finding against a niche alpha release.

An attacker with network access to a tika-server instance running 4.0.0-alpha-1 - where the operator has set enableUnsecureFeatures=false to restrict dangerous endpoints - sends a crafted HTTP request directly to the /unpack endpoint with a malicious or oversized archive payload. Because the endpoint does not check the enableUnsecureFeatures flag, it processes the archive normally despite the restriction, potentially causing excessive resource consumption or triggering vulnerable parser behavior on attacker-controlled content. No public exploit code has been identified at time of analysis.