LightRAG exposes a RESTful API server that, by default, listens on all network interfaces without enabling authentication. An unauthenticated attacker on the same network can therefore exercise any endpoint, reading documents, uploading or deleting files, altering the knowledge graph, cancelling running pipelines, clearing caches, and consuming large language model resources. This unrestricted access effectively compromises data confidentiality, integrity, and availability.

The vulnerability affects the HKUDS LightRAG distribution. All releases up to and including 1.5.4 are impacted. Users running these versions, or any unpatched earlier iterations, are susceptible unless they have manually disabled the API or set up custom authentication. The fix is incorporated in 1.5.5rc1 and later.

The CVSS score of 9.8 classifies the flaw as Critical. The EPSS score is not publicly available, and the vulnerability is not listed in the CISA KEV catalog, but the default open configuration removes the gating required to exploit the APIs. An attacker can obtain the list of available endpoints and interact with them via simple HTTP requests, implying a low barrier to initial compromise. Unauthenticated attackers can read sensitive content and exhaust LLM resources, which could lead to denial‑of‑service for legitimate users.