4h ago

Bun Runs 24/7 Fuzzer With Claude AI For Parser Security Fixes

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Original post
OPJarred Sumner#1715Jarred Sumner@JARREDSUMNER

There is now a fuzzer running 24/7 for every language parser in Bun, ranging from .npmrc files and .patch files to shell scripts to jsonc & typescript & css. Once it minimizes a repro, it sends to Claude to fix and then I review.

6:26 AM · May 24, 2026 View on X
REPLYJarred Sumner#1715Jarred Sumner@JARREDSUMNER

For the JS parser fuzzer, I set it up to use swc’s test suite as the corpus and then change & permute “interesting” characters. Their existing tests already cover lots of edgecases, so it’s an especially good one to fuzz with.

Jarred SumnerJarred Sumner@jarredsumner

There is now a fuzzer running 24/7 for every language parser in Bun, ranging from .npmrc files and .patch files to shell scripts to jsonc & typescript & css. Once it minimizes a repro, it sends to Claude to fix and then I review.

1:26 PM · May 24, 2026 · 6.3K Views
1:28 PM · May 24, 2026 · 5.5K Views