fix: decode WHATWG-escaped characters in file originalname (#836)#1421
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fix: decode WHATWG-escaped characters in file originalname (#836)#1421webdevelopersrinu wants to merge 1 commit into
webdevelopersrinu wants to merge 1 commit into
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Browsers escape the bytes 0x0A (LF), 0x0D (CR) and 0x22 (") as %0A, %0D
and %22 when serialising filenames in a multipart/form-data body, per the
WHATWG HTML spec. Busboy leaves them escaped, so a file named `file".ext`
was exposed as `file%22.ext` on `req.file.originalname`.
Reverse exactly those three sequences when building the file object. Only
these are decoded on purpose: a bare `%` is never escaped by the spec, so
a full decodeURIComponent would corrupt legitimate names like `50%.pdf`.
Adds regression tests covering the escaped quote, CR/LF, an unescaped
name, and preservation of a literal percent sign.
Fixes expressjs#836
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What & why
Fixes #836.
Browsers escape the bytes
0x0A(LF),0x0D(CR) and0x22(") as%0A,%0Dand%22when serialising a filename in amultipart/form-databody, per the WHATWG HTML spec. Busboy leavesthem escaped, so a file uploaded as
file".extwas exposed onreq.file.originalnameasfile%22.ext.Change
lib/make-middleware.js.%is never escapedby the spec, so a full
decodeURIComponentwould corrupt legitimate nameslike
50%off.pdf. A dedicated test guards this.Reproduction (before)
Uploading a file named
file".ext→req.file.originalname === 'file%22.ext' // ❌ before
req.file.originalname === 'file".ext' // ✅ after
Tests
Adds
test/filename-decoding.jscovering:%22)%0D,%0A)50%off.ext)All pass;
standardlint is clean. Targeting the 2.x line as discussed onthe issue.