https://dergoegge.de/blog.html Posts and publications by Niklas Gögge. en https://dergoegge.de/blog/somethings-been-bugging-me.html https://dergoegge.de/blog/somethings-been-bugging-me.html Wed, 09 Sep 2026 00:00:00 GMT Recent multi-million dollar exploits show that LLMs have made vulnerability discovery dramatically cheaper, and the Bitcoin community has responded with large-scale LLM scanning. But a security model that hinges on access to the latest frontier model is not sustainable. Bitcoin Core and secp256k1 have held up well, and their exhaustive, continuous fuzzing is likely a big reason why. Projects should use LLMs to lower the cost of building that kind of testing infrastructure, not just to find bugs. https://brink.dev/blog/2026/06/25/bedrock-deterministic-hypervisor/ https://brink.dev/blog/2026/06/25/bedrock-deterministic-hypervisor/ Thu, 25 Jun 2026 00:00:00 GMT Bedrock is a deterministic hypervisor built from scratch in Rust, acting as a determinism boundary between the software under test and the hardware beneath it to eliminate sources of non-determinism. The post focuses on emulating time precisely enough to inject timer interrupts at exact instruction counts, progressing through increasingly sophisticated techniques up to EPT-friendly PEBS to achieve near-zero skid. https://brink.dev/blog/2026/04/09/fuzzamoto-non-determinism/ https://brink.dev/blog/2026/04/09/fuzzamoto-non-determinism/ Thu, 09 Apr 2026 00:00:00 GMT Non-determinism undermines fuzzing effectiveness by causing flaky crashes and bloated corpora. This post explores its sources—from hardware timing and randomness to accumulated global state—and explains how Fuzzamoto uses VM snapshots and targeted patches to achieve sufficient determinism for practical Bitcoin node fuzzing. https://brink.dev/blog/2026/01/07/fuzzamoto-introduction/ https://brink.dev/blog/2026/01/07/fuzzamoto-introduction/ Wed, 07 Jan 2026 00:00:00 GMT Fuzzamoto is an external fuzz testing suite for Bitcoin full nodes that uses snapshot fuzzing with VMs to run full-system simulations. This is the first part of a series of blog posts, covering motivation, design insights, and an example of a bug it found. https://delvingbitcoin.org/t/cve-2024-38365-public-disclosure-btcd-findanddelete-bug/1184 https://delvingbitcoin.org/t/cve-2024-38365-public-disclosure-btcd-findanddelete-bug/1184 Thu, 10 Oct 2024 00:00:00 GMT Btcd incorrectly implemented the FindAndDelete operation for legacy signature verification, removing any data push containing a signature rather than only exact matches. This discrepancy allowed standard transactions to cause chain splits between btcd and Bitcoin Core. https://bitcoincore.org/en/2024/10/08/disclose-blocktxn-crash/ https://bitcoincore.org/en/2024/10/08/disclose-blocktxn-crash/ Tue, 08 Oct 2024 00:00:00 GMT A bug in Bitcoin Core's compact block handling allowed remote attackers to crash nodes by sending a malicious blocktxn message. The issue occurred because state wasn't properly cleared after collision detection, causing an assertion failure on a second FillBlock call. https://delvingbitcoin.org/t/disclosure-btcd-consensus-bugs-due-to-usage-of-signed-transaction-version/455 https://delvingbitcoin.org/t/disclosure-btcd-consensus-bugs-due-to-usage-of-signed-transaction-version/455 Mon, 22 Jan 2024 00:00:00 GMT Btcd incorrectly treated transaction versions as signed integers when validating BIP 68 and BIP 112 relative timelocks. This could cause chain splits between btcd and Bitcoin Core, putting Lightning Network users at risk of fund loss. Found via differential fuzzing. https://delvingbitcoin.org/t/denial-of-service-bugs-in-lnds-channel-update-gossip-handling/314 https://delvingbitcoin.org/t/denial-of-service-bugs-in-lnds-channel-update-gossip-handling/314 Thu, 21 Dec 2023 00:00:00 GMT Two denial-of-service bugs in LND's gossip handling. One exploited an unbounded buffer for premature channel updates to cause memory exhaustion. The other applied rate limits before signature validation, allowing attackers to censor valid updates through spam. https://arxiv.org/pdf/2205.12737 https://arxiv.org/pdf/2205.12737 Wed, 25 May 2022 00:00:00 GMT Research paper investigating gossip protocol delays in the Lightning Network. We measured actual convergence delays, found they are significantly larger than protocol specs suggest, and proposed solutions ranging from parameter tweaks to protocol redesigns. https://blog.mozilla.org/security/2021/07/12/firefox-90-supports-fetch-metadata-request-headers/ https://blog.mozilla.org/security/2021/07/12/firefox-90-supports-fetch-metadata-request-headers/ Mon, 12 Jul 2021 00:00:00 GMT Firefox 90 added support for Fetch Metadata Request Headers, enabling servers to protect against cross-site request forgery, cross-site leaks, and Spectre attacks. Headers like Sec-Fetch-Site let servers distinguish legitimate requests from malicious ones.