CVE-2026-72711: Lean 4 kernel soundness bug — inference cache poisoning via opaque declarations (0 = 1 demonstrated)

Summary by Cyber Security News26 Oct 2026, 01:14 CET

About this summary. This is a short excerpt from the description that oss-security published with its article. Cyber Security News did not report or verify the underlying story. Read the original: https://seclists.org/oss-sec/2026/q4/380

Posted by Jonathan Brossard on Oct 25 1. Summary A soundness bug in the Lean 4 kernel allows construction of a checked proof of False — and by extension, any proposition, including 0 = 1 — without axioms, sorry, unsafeCast, debug.skipKernelTC, or modified .olean files. The proof passes the kernel at maximum checking (--trust=0).

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