--- title: Most RAG Hallucinations Are Retrieval Failures: How the... description: Most hallucinations in RAG systems stem from retrieval failures, not the language model inventing facts. Using the NIST Cybersecurity Framework as a concrete... canonical: https://daily.dev/posts/most-rag-hallucinations-are-retrieval-failures-how-the-retrieval-brick-decides-what-the-model-can-i-8ajbd1sn7 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Most RAG Hallucinations Are Retrieval Failures: How the Retrieval Brick Decides What the Model Can Invent | daily.dev og:description: Most hallucinations in RAG systems stem from retrieval failures, not the language model inventing facts. Using the NIST Cybersecurity Framework as a concrete... og:url: https://daily.dev/posts/most-rag-hallucinations-are-retrieval-failures-how-the-retrieval-brick-decides-what-the-model-can-i-8ajbd1sn7 og:image: https://api.daily.dev/og/posts/8aJbd1sn7.png og:image:alt: Most RAG Hallucinations Are Retrieval Failures: How the Retrieval Brick Decides What the Model Can Invent og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Most RAG Hallucinations Are Retrieval Failures: How the Retrieval Brick Decides What the Model Can Invent **[Towards Data Science](https://daily.dev/sources/tds)** · 12 min read · 2 upvotes · 0 comments ## Summary Most hallucinations in RAG systems stem from retrieval failures, not the language model inventing facts. Using the NIST Cybersecurity Framework as a concrete example, the author demonstrates that naive cosine similarity ranked the correct answer (backup practices in PR.IP-4) dead last out of 55 pages, while a simple keyword match ranked it first. Three retrieval failure modes are identified: the answer not being retrieved at all, the wrong passage being retrieved, and the answer being buried among distractors. The fix is a two-part retrieval discipline: anchor on the right span using keyword matching, document structure, and embeddings as parallel signals, then scope the context tightly around that anchor. A typed answer contract at the generation layer serves as a second line of defense. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Your RAG Isn’t Hallucinating. Retrieval Handed It the Wrong Chunk.](https://daily.dev/posts/your-rag-isn-t-hallucinating-retrieval-handed-it-the-wrong-chunk--tw9lco7qx) · Medium · 1 upvotes · 0 comments - [Your LLM Is Only as Good as What It Retrieves](https://daily.dev/posts/your-llm-is-only-as-good-as-what-it-retrieves-q3fmcuq2k) · Weaviate · 0 upvotes · 0 comments - [Why production RAG systems give confident, wrong answers at scale](https://daily.dev/posts/why-production-rag-systems-give-confident-wrong-answers-at-scale-7b6euvauc) · The New Stack · 0 upvotes · 0 comments --- Tags: [#llm](https://daily.dev/tags/llm), [#rag](https://daily.dev/tags/rag), [#vector-search](https://daily.dev/tags/vector-search) [View this post on daily.dev](https://daily.dev/posts/most-rag-hallucinations-are-retrieval-failures-how-the-retrieval-brick-decides-what-the-model-can-i-8ajbd1sn7) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Most RAG Hallucinations Are Retrieval Failures: How the Retrieval Brick Decides What the Model Can Invent","url":"https://daily.dev/posts/most-rag-hallucinations-are-retrieval-failures-how-the-retrieval-brick-decides-what-the-model-can-i-8ajbd1sn7","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/most-rag-hallucinations-are-retrieval-failures-how-the-retrieval-brick-decides-what-the-model-can-i-8ajbd1sn7"},"datePublished":"2026-07-15T12:20:48.102Z","dateModified":"2026-07-15T14:22:08.781Z","description":"Most hallucinations in RAG systems stem from retrieval failures, not the language model inventing facts. 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