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Critical vulnerability in JWT decode method #1

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Critical vulnerability in JWT decode method #1

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930d739
Update decode method to fix algo vulnerability
andrea-wood May 11, 2016
3a849e0
Add algo parameter to decode example
andrea-wood May 11, 2016
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2 changes: 1 addition & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ $token = array(
);

$jwt = JWT::encode($token, $key);
$decoded = JWT::decode($jwt, $key);
$decoded = JWT::decode($jwt, $key, 'HS256');

print_r($decoded);
?>
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5 changes: 4 additions & 1 deletion lib/JWT/Authentication/JWT.php
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Expand Up @@ -32,7 +32,7 @@ class JWT
* @uses jsonDecode
* @uses urlsafeB64Decode
*/
public static function decode($jwt, $key = null, $verify = true)
public static function decode($jwt, $key = null, $algo = null, $verify = true)
{
$tks = explode('.', $jwt);
if (count($tks) != 3) {
Expand All @@ -50,6 +50,9 @@ public static function decode($jwt, $key = null, $verify = true)
if (empty($header->alg)) {
throw new \DomainException('Empty algorithm');
}
if($algo && $header->alg !== $algo){
throw new \DomainException('Invalid algorithm');
}
if ($sig != JWT::sign("$headb64.$bodyb64", $key, $header->alg)) {
throw new \UnexpectedValueException('Signature verification failed');
}
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