LightLLM EUVD-2026-89483

Requires the LightLLM server (through v1.2.0) to be started with the non-default --pd_trans_mode nccl flag, which enables the NCCL-based KV-transfer control channel for prefill-decode disaggregation. Under that mode the exposed_set_value method is reachable over the network without authentication (PR:N, UI:N) and accepts unbounded key-value storage with no size or count limit. Limiting factors: the NCCL transport mode is opt-in and not the default, and the control channel must be network-reachable to the attacker; default LightLLM deployments without this flag are not exposed. Impact is availability-only (worker crash / node failure) - no data disclosure or modification.

This is a genuine but bounded availability threat. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VA:H) describes a network-reachable, low-complexity, unauthenticated denial-of-service with high availability impact and zero confidentiality or integrity impact - consistent with the CWE-770 (unbounded resource allocation) memory-exhaustion described. No EPSS score, no CISA KEV listing, and no public exploit were provided, so the correct read is 'no public exploit identified at time of analysis.' The 8.7 score is driven almost entirely by the availability metric under the newer 4.0 scoring, which weights an unauthenticated remote DoS heavily; this is a real, if single-dimension, risk rather than an inflated critical. The exploitation is strictly conditional: it only exists when the server is launched with the non-default --pd_trans_mode nccl flag, which meaningfully narrows the real-world attack surface. Net: prioritize for operators actually running LightLLM in prefill-decode disaggregation mode with NCCL transport exposed on the network; deprioritize elsewhere, since the default deployment is not affected.

An attacker with network reach to a LightLLM node running in NCCL prefill-decode transfer mode repeatedly invokes the unauthenticated exposed_set_value RPC method on the KV-transfer worker, storing arbitrarily large or numerous key-value pairs with no size or count limit. The worker's memory grows until the process crashes, taking the node down. No public exploit code was identified at time of analysis, but the attack is trivial to script given the low complexity and lack of authentication.