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Fencer Intel
no cvss —

GO-2026-4950 json

Authorization bypass via double-encoded paths in github.com/valyala/fasthttp

published 2mo ago modified 2mo ago

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
—
no score, EPSS covers CVEs only
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/valyala/fasthttp 1.70.0

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Affected packages

ecosystem package affected fixed in
go github.com/valyala/fasthttp
<1.70.0
1.70.0

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.