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  Who is to blame for the recent freezer attacks? Freezer controllers * were directly connected to mobile networks, _accessible to anyone_ * had a hardwired password: the _current date_ ‼️ * had _no_ over-the-air update possibility * had reached _end-of-life_ years ago: https://en.wikipedia.org/wiki/2026_European_cold_chain_hacks

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  I have been selected into the inaugural class of the ACM SIGSOFT Software Engineering Academy: https://www2.sigsoft.org/academy/inaugural-class.html

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  In the past months, I have had a number of great PhD students pass their exams: * Leon Bettscheider for "Input Grammars in Practice - Methods for Symbolic Mining, Systematic Evaluation, and Grey-Box Testing": https://scholar.google.com/citations?user=GNt3lsUAAAAJ&hl=en&oi=ao * Masudul Hasan Masud for "Addressing Socio-Technical Blind Spots in Modern Software Systems": https://www.linkedin.com/feed/update/urn:li:activity:7471651787322634241/...

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  There's an ICSE 2020 paper of mine, "Debugging Inputs", that, according to Google Scholar, has a whopping 12,800 citations. Most cited paper ever? Alas, ACM DL is closer to the truth with 1 citation (actually, a self-citation). Does anyone know how to report wrong numbers to the Google Scholar team?

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  At #Dagstuhl with my team and a few guests, setting our research agenda for the next 12 months. Big things coming!

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  Proud greetings from the 💃 #Fandango headquarters! The all-new 1.2 release of our specification-guided #Fandango fuzzer brings many under-the-hood improvements, along with new, useful user-facing features and documentation. Check out the release notes! https://fandango-fuzzer.github.io/ReleaseNotes.html

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  On my way to Bochum for the PhD exam of Niklas Risse (with co-examiners Marcel Böhme and Michael Pradel)

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  The #Fandango team is pulling off a long evening session because their advisor insists that the paper be ready one day _before_ the deadline

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  I will be presenting our latest #Fandango work at the #GOTO conference on September 30 in Copenhagen, Denmark. Let's meet at GOTO! https://gotocph.com/2026

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  Introducing #Fanbase - a curated collection of #Fandango file format specifications: Use `fandango fuzz -F png -n 1000` to generate 1,000 PNG files for testing. Starting with PNG, GIF, JPG, and other image formats today; more formats every Tuesday. Enjoy! https://github.com/fandango-fuzzer/fanbase

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  Talk slides and details for "The Devil's Guide to Doing your PhD" are now available. See you on Monday at #ASE2026! https://conf.researchr.org/details/ase-2026/ase-2026-doctoral-symposium/1/The-Devil-s-Guide-to-Doing-your-PhD

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  Talk slides and details for "On Impact in Software Engineering Research" are now available. See you on Monday at #ASE2026: https://conf.researchr.org/details/ase-2026/ase-2026-new-faculty-symposium/6/On-Impact-in-SE-Research

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  At #ASE2026 tomorrow, visit these workshop presentations by my students Tural and Marius: * How Grammar-Based Synthetic Data Shapes Behavior Learning: An Empirical Study of Input Generation Strategies * Can Open-Weight LLMs Predict Test Outcomes from Traces? A Cross-Subject Boundary Study on Tests4Py * Failure Explanations: The Missing Abstraction between Debugging and Repair * Execution Features and Their Relations to Faults: A Replication on Defects4J All details: https://conf.researchr.o...

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  RE: https://mastodon.social/@AndreasZeller/117393145423966731 New fuzzing formats for #Fandango! Today, we added HEIC, JXL, PPM, SVG, XBM, and XPM to the set of #Fanbase formats. Use `fandango fuzz -F heic -n 1000` to generate 1,000 HEIC files for testing. Special thanks to José Antonio "Pepe" Zamudio Amaya and Norman Becker for preparing this release. Next Tuesday: audio formats! https://github.com/fandango-fuzzer/fanbase

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  How can you tailor a test generator to focus on specific software features? At #ASE2026 today, José Antonio "Pepe" Zamudio Amaya presents our "Compás" work on "feature-focused test generation". Talk details and paper here: https://conf.researchr.org/details/ase-2026/ase-2026-research-track/183/Feature-Focused-Test-Generation

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  Never Gonna Give You Up! This week, we're releasing five audio formats (WAV, FLAC, Ogg, MP3, and AAC) for #Fandango: use `fandango fuzz -F aac -n 1000` to generate 1,000 AAC files for testing. Unfortunately, Fandango can't synthesize Rick Astley - but it can definitely test your boundaries :-) https://github.com/fandango-fuzzer/fanbase

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  "But do you find bugs with #Fandango?" You bet! This Summer, we reported more than 100 bugs and vulnerabilities to library and app maintainers. Here's a crash my student Norman Becker found in Apple Music using the #Fanbase audio specs we released on Tuesday: https://support.apple.com/en-mn/127115

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  Fuzzing archive formats! This week, we're releasing eight new archive formats for #Fandango (zip, tar, 7z, rar, cab, cpio, arj, and ar); use `fandango fuzz -F tar -n 1000` to generate 1,000 tar files for testing. Enjoy! https://github.com/fandango-fuzzer/fanbase

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  Neural program modeling! Our newest server sports eight Nvidia RTX PRO 6000 GPU cards and 1.5 TB of RAM to train machine learning models that replicate the behavior of existing programs. The resulting models can instantly predict inputs for desired execution features, predict the coverage of given inputs, and even replace the original program for safe testing. (When not busy, the server can run Doom, too – 17,208 instances in parallel) Read more in our recent TOSEM paper: https://dl.acm.org/doi/...

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  Advice to young researchers! On Monday at #ASE2026 in Munich, I will be giving two talks: * "The Devil's Guide to Doing your PhD" at the Doctoral Symposium; and * "On Impact in Software Engineering Research" at the New Faculty Symposium. Will post all slides after the talks. Meet me at ASE!

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  Besides code coverage, there are several execution features that can correlate with failure and thus help in localizing faults. See the talk of Marius Smytzek today 15:00 at #FSE2026: https://conf.researchr.org/details/fse-2026/fse-2026-journal-first/9/How-Execution-Features-Relate-to-Failures-An-Empirical-Study-and-Diagnosis-Approach

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  Reunited after 20 years! These are Jacek Śliwerski, Tom Zimmermann, and Andreas Zeller, meeting twenty years after creating the foundational #SZZ algorithm to relate bugs to associated changes. See us telling the story of the work in our impact paper award session, Wednesday at 08:30: https://conf.researchr.org/details/fse-2026/fse-2026-plenary-events/4/SIGSOFT-Impact-Award-Talk-When-do-changes-induce-fixes-

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  Back again! Five weeks ago, an artificial lens in my right eye had dislocated itself; I was effectively one-eyed, and my doctors strongly discouraged me from reading - so, lots of talking and phoning, but only the most important mails, and no papers at all. I now had surgery, and things look good. It‘ll take me weeks to catch up with mails and reviews, but I’ll see you soon, starting at #FSE next week!

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  I got interviewed by Nature on how to catch bugs in scientific software. My "Basics of Debugging 101" were: 1. Proceed systematically 2. Find out when the bug occurs 3. Explain the bug to a rubber duck 4. Write tests that replicate the bug Enjoy the read! https://www.nature.com/articles/d41586-026-01261-w

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  When formatted as a PDF, @TheFuzzingBook now has 1,477 pages

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  How do execution features relate to failures? In this new @ACM TOSEM paper, Marius Smytzek, Martin Eberlein, Lars Grunske, and I analyze which execution features beyond code coverage correlate best with failures and lead to accurate explanations of failure causes: https://dl.acm.org/doi/10.1145/3783989

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  Starting this year, I will only review for conferences that get rid of a "bidding" phase, as allowing reviewers to bid on papers they want to review opens too many opportunities for manipulation and collusion. For details, see https://andreas-zeller.info/2025/12/07/Reviewer-Author-Collusion-Rings-and-How-to-Fight-Them.html #nobidding

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  About time: A multi-celebration for becoming a member of Academia Europaea, my SIGSOFT Influential Educator Award, my 60th birthday, becoming an IEEE Fellow, _and_ getting the 2026 IEEE Harlan D. Mills Award. With cake and fizzy drinks!

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  #Fandango 1.1 is now available! With this release, #Fandango becomes a full-fledged _protocol fuzzer_, happily exploring states and messages of protocols such as FTP or DNS. Thanks to José Antonio Zamudio Amaya. Valentin Huber, Alexander Liggesmeyer, and Marius Smytzek for their hard work! Find Fandango at https://fandango-fuzzer.github.io/

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  On my way to Savannah, Georgia to an IFIP WG 4.3 meeting, where I’ll present our work on Parameterized Compiler Testing (a joint work with my fantastic co-workers Addison Crump and Alexi Turcotte)