{
  "slug": "specification-gap",
  "term": "Specification gap",
  "definition": "A mismatch between the property that was formally proved and the property that was actually needed, so a valid proof fails to cover real behaviour.",
  "detail": [
    "The public example is sp1-lean's JALR theorem, which assumed a 4-byte-aligned jump target and therefore did not cover legitimate programs; the Ethereum Foundation disclosed the bug in May 2026. The Verification Theatre paper documents the same phenomenon in verified ML-KEM code. Reading the theorem statements and assumptions is as important as checking that the proof compiles."
  ],
  "page": "https://sorryfree.com/glossary/specification-gap/",
  "updated": "2026-09-13"
}