GO-2026-4950None▾ SunlitAuthorization bypass via double-encoded paths in github.com/valyala/fasthttp
▾ Sunlit zone — Low / medium · no exploitation signal
impact 2.8 · likelihood 0 · exploitation 0
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Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
In github.com/valyala/fasthttp before 1.70.0, ServeFile and ServeFS reinterpret filesystem paths as URIs, decoding percent-encoded sequences and treating characters like '?' and '#' as URI delimiters. In applications where authorization guards inspect ctx.Path() before passing paths to file-serving handlers, double-encoded path variants (e.g., /%2561dmin/export.csv) bypass access controls while still resolving to the protected file on disk.
github.com/valyala/fasthttp < 1.70.0Upgrade to a patched release:
github.com/valyala/fasthttp 1.70.0Connected by shared product, vendor, weakness, or advisory.