Summary
minimatch is vulnerable to Regular Expression Denial of Service (ReDoS) when a glob pattern contains many consecutive * wildcards followed by a literal character that doesn't appear in the test string. Each * compiles to a separate [^/]*? regex group, and when the match fails, V8's regex engine backtracks exponentially across all possible splits.
The time complexity is O(4^N) where N is the number of * characters. With N=15, a single minimatch() call takes ~2 seconds. With N=34, it hangs effectively forever.
Details
Give all details on the vulnerability. Pointing to the incriminated source code is very helpful for the maintainer.
PoC
When minimatch compiles a glob pattern, each * becomes [^/]*? in the generated regex. For a pattern like ***************X***:
/^(?!\.)[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?X[^/]*?[^/]*?[^/]*?$/
When the test string doesn't contain X, the regex engine must try every possible way to distribute the characters across all the [^/]*? groups before concluding no match exists. With N groups and M characters, this is O(C(N+M, N)) — exponential.
Impact
Any application that passes user-controlled strings to minimatch() as the pattern argument is vulnerable to DoS. This includes:
- File search/filter UIs that accept glob patterns
.gitignore-style filtering with user-defined rules
- Build tools that accept glob configuration
- Any API that exposes glob matching to untrusted input
Thanks to @ljharb for back-porting the fix to legacy versions of minimatch.
References
Summary
minimatchis vulnerable to Regular Expression Denial of Service (ReDoS) when a glob pattern contains many consecutive*wildcards followed by a literal character that doesn't appear in the test string. Each*compiles to a separate[^/]*?regex group, and when the match fails, V8's regex engine backtracks exponentially across all possible splits.The time complexity is O(4^N) where N is the number of
*characters. With N=15, a singleminimatch()call takes ~2 seconds. With N=34, it hangs effectively forever.Details
Give all details on the vulnerability. Pointing to the incriminated source code is very helpful for the maintainer.
PoC
When minimatch compiles a glob pattern, each
*becomes[^/]*?in the generated regex. For a pattern like***************X***:When the test string doesn't contain
X, the regex engine must try every possible way to distribute the characters across all the[^/]*?groups before concluding no match exists. With N groups and M characters, this is O(C(N+M, N)) — exponential.Impact
Any application that passes user-controlled strings to
minimatch()as the pattern argument is vulnerable to DoS. This includes:.gitignore-style filtering with user-defined rulesThanks to @ljharb for back-porting the fix to legacy versions of minimatch.
References