Updated 3/9/2026
Semantic caching mechanisms in LLM applications are vulnerable to cross-tenant cache key collision attacks (CacheAttack) due to the inherent mathematical conflict between locality-preserving fuzzy hashing and cryptographic collision resistance (the avalanche effect). An attacker can leverage gradient-based search algorithms to optimize an adversarial discrete suffix that, when appended to a malicious prompt, forces its output embedding vector to collide with the embedding of a targeted benign…
From Similarity to Vulnerability: Key Collision Attack on LLM Semantic Caching
Affects: Llama 3.1 8B, Mistral 7B, DeepSeek R1
Source: arXiv