Christian Holler
Principal Security Engineer at Mozilla
Bonn, North Rhine-Westphalia, Germany
Summary
🤩
Rockstar🎓
Top SchoolChristian Holler is a Principal Security Engineer at Mozilla with 14+ years of experience specializing in fuzzing, dynamic and static analysis, and hardening large-scale browser codebases. He combines deep systems and C++ expertise—evident from sustained contributions to Gecko/SpiderMonkey and OSS-Fuzz—with automation and QA skills that improved build stability and crash analysis workflows for high-profile projects like Firefox and OSS-Fuzz. As a Firefox Tech Lead he shapes security and stability strategy across teams while still shipping hands-on fixes and fuzzers (e.g., enhancements to The Fuzzing Book and funfuzz). Based in Bonn, he brings an unusual practical security perspective from consulting on physical locks and competitive non-destructive lock opening, applying real-world attack thinking to software defenses. Colleagues rely on him for pragmatic, tool-driven solutions that bridge low-level memory safety, CI/build engineering, and reproducible crash triage.
14 years of coding experience
15 years of employment as a software developer
Master of Science (M.Sc.) Informatik, Master of Science (M.Sc.) Informatik at Universität des Saarlandes
Github Skills (27)
debug10
javascript10
c-language10
python10
scripting10
testing10
memory-management10
automation10
script10
build-automation10
sh10
fuzzing10
automated-tests10
automations10
shell10
Programming languages (17)
Github contributions (5)
MozillaSecurity/funfuzz
Aug 2011 - Dec 2021
A collection of fuzzers in a harness for testing the SpiderMonkey JavaScript engine.
Role in this project:
Back-end Developer & Test Automation Engineer
Back-end Developer & Test Automation EngineerContributions:35 commits, 2 PRs, 12 pushes in 10 years 5 months
Contributions summary:Christian primarily focused on enhancing the fuzzing capabilities of the SpiderMonkey JavaScript engine. They modified the autoBisect script to improve exit code handling and string output, contributing to better automated testing. Key contributions include adding new detectors for assertions, crashes, and leaks, improving the detection of potential issues in the JavaScript engine. Furthermore, the user implemented fixes and improvements to compilation processes and flags, especially related to ICU headers and thread-safe configurations.
javascript-enginespidermonkey-enginespidermonkeytestingjavascript
mozilla/gecko-dev
Sep 2013 - Jan 2023
Read-only Git mirror of the Mercurial gecko repositories at https://hg.mozilla.org. How to contribute: https://firefox-source-docs.mozilla.org/contributing/contribution_quickref.html
Role in this project:Back-end Developer / Software Engineer
Back-end Developer / Software EngineerContributions:315 commits in 9 years 5 months
Contributions summary:Christian primarily contributes to the Mozilla Gecko engine, focusing on bug fixes and feature enhancements related to the core browser functionality. Their commits involve modifying C++ code in areas such as anti-tracking, service workers, JavaScript runtime, and blob handling. They demonstrate a strong understanding of low-level systems programming, memory management, and the internal workings of the browser's components. Their contributions address issues related to memory management, fuzzing, and security considerations, highlighting their expertise in building robust and secure software.
repositoriesfirefoxmercurialgit-mirrormozilla
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