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fix: prevent path traversal in functions:create command [security] #8207

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fix: prevent path traversal in functions:create command [security] #8207

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094e830
fix: prevent path traversal in functions:create command
NiteshCodes7 Apr 24, 2026
864e2da
extra comment removed
NiteshCodes7 Apr 24, 2026
b466368
Merge branch 'main' into fix/path-traversal-functions-create
NiteshCodes7 Apr 27, 2026
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42 changes: 21 additions & 21 deletions package-lock.json
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24 changes: 16 additions & 8 deletions src/commands/functions/functions-create.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -394,7 +394,9 @@ const downloadFromURL = async function (command, options, argumentName, function
folderContents.map(async ({ download_url: downloadUrl, name }) => {
try {
const res = await fetch(downloadUrl)
const finalName = path.basename(name, '.js') === functionName ? `${nameToUse}.js` : name
const finalName = path.basename(name, '.js') === functionName
? `${nameToUse}.js`
: path.basename(name) // ← strip any directory components
const dest = fs.createWriteStream(path.join(fnFolder, finalName))
res.body?.pipe(dest)
} catch (error_) {
Expand Down Expand Up @@ -744,14 +746,20 @@ const registerEFInToml = async (funcName, options) => {
* @returns
*/
// @ts-expect-error TS(7006) FIXME: Parameter 'functionsDir' implicitly has an 'any' t... Remove this comment to see the full error message
const ensureFunctionPathIsOk = function (functionsDir, name) {
const functionPath = path.join(functionsDir, name)
if (fs.existsSync(functionPath)) {
log(`${NETLIFYDEVLOG} Function ${functionPath} already exists, cancelling...`)
process.exit(1)
const ensureFunctionPathIsOk = function (functionsDir, name) {
// Prevent path traversal: reject names like "../../evil"
const resolvedFunctionsDir = path.resolve(functionsDir)
const functionPath = path.join(resolvedFunctionsDir, name)
if (!functionPath.startsWith(resolvedFunctionsDir + path.sep)) {
log(`${NETLIFYDEVERR} Invalid function name: "${name}" resolves outside the functions directory.`)
process.exit(1)
}
if (fs.existsSync(functionPath)) {
log(`${NETLIFYDEVLOG} Function ${functionPath} already exists, cancelling...`)
process.exit(1)
}
return functionPath
}
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return functionPath
}

// Scans `functions-templates/<lang>` for a template whose `.mjs` metadata
// `name` matches. Returns its `functionType` and the language folder it lives
Expand Down