arXiv AI

LaCache: Robust Semantic Caching for LLM Serving

LaCache introduces a redesigned semantic caching mechanism for large language model (LLM) serving that defends against cache‑collision attacks. By shifting integrity checks from queries to the first $k$ speculatively decoded tokens of the LLM response, LaCache can detect adversarial cache pollution with provable high probability. Experiments across multiple LLMs and benchmarks show that LaCache reduces attack hit rates to near zero while retaining over 90% of benign cache utility.

arXiv AI
Jun 3

Inference Cost Attacks for Retrieval-Augmented Large Language Models

arXiv:2606. 02643v1 Announce Type: cross Abstract: Retrieval-Augmented Generation (RAG)-enhanced LLM systems, while powerful, introduce substantial inference costs due to the inclusion of an extra multi-stage pipeline that dynamically retrieves and synthesizes information from external knowledge sources.

By Chengliang Liu, Liangbo Ning, Yujuan Ding, Wenqi Fan
arXiv Computation and Language
Aug 31

A Wolf in Sheep's Clothing: Targeted Routing Hijacking in Federated RAG

The paper exposes a new vulnerability in Federated Retrieval-Augmented Generation (FedRAG) called Routing Hijacking, where a malicious client forges its semantic profile to attract target queries despite lacking relevant data. Experiments across three FedRAG routing architectures show that this attack consistently misroutes queries, causing downstream failures such as missing evidence, poisoning, incorrect answers, hallucinations, and sycophantic behavior. The authors propose a trust‑aware post‑routing framework that reweights clients based on evidence feedback, which effectively suppresses persistent hijacking and transfers to a learned neural router.

By Junjie Mu, Qiongxiu Li
arXiv Computation and Language
Aug 31

CamoDocs: A Poisoning Attack Against Retrieval-Augmented Language Models Using Camouflaged Documents

arXiv:2608. 28389v1 Announce Type: cross Abstract: Retrieval-augmented generation (RAG) augments LLMs with external documents, but public or user-editable sources expose RAG systems to data poisoning: attackers can inject malicious documents to steer outputs toward targeted answers.

By Jaewon Jung, Haizhong Zheng, Hongsun Jang, Jaeyong Song, Beidi Chen, Jinho Lee
arXiv AI
Sep 10

Detokenization Leaks: Reconstructing Local LLM Outputs From Cache Traces

The paper introduces an attack that reconstructs text generated by locally hosted large language models by monitoring CPU cache activity during detokenization. It uses Flush+Reload on shared tokenizer code to time decoding, then Prime+Probe to capture token‑dependent cache traces, followed by a clustering‑and‑language‑model pipeline to recover the output text. The method is evaluated across various datasets, hardware, inference frameworks, and model families, successfully retrieving semantically accurate outputs from real‑world local LLM deployments, including agentic systems.

By Roy Weiss, Benyamin Konstantinov, Eitam Sheetrit, Tomer Simon, Yisroel Mirsky
arXiv Computation and Language
3d ago

Multi-Turn Semantic Caching for Low-Cost LLM Serving

The paper introduces two algorithms—CUCB‑SC‑MT and CLCB‑LS‑MT—for multi‑turn semantic caching in large language model serving. These methods learn a "reuse risk" metric from judge feedback to decide which conversation states to cache, balancing avoided generation cost against the risk of unacceptable reuse. Experiments on math‑tutoring and movie‑ticketing dialogues show that the online CLCB‑LS‑MT algorithm reduces generation cost by 35–41% and estimated latency by 19–35% compared to prior caching approaches.

By Baran Atalar, Selly Beyene, Xutong Liu, Carlee Joe-Wong