guzzlehttp/psr7 did not reject URI host components containing authority delimiters (/, ?, #, @, or ), an embedded port such as host:8080, or IPv6 brackets that do not frame the host (such as [::1 or ::1]). Uri::assertValidHost() rejected only control characters, so these malformed hosts were accepted both when parsing a URI string — including through new Uri(), an absolute-form request target passed to Message::parseRequest(), and the synthetic SERVER_NAME or …
guzzlehttp/psr7 did not reject CR/LF characters in certain first-party HTTP start-line fields: the request method, protocol version, and response reason phrase. If an application placed attacker-controlled data into one of those fields and later serialized the PSR-7 message as raw HTTP/1.x, for example with Message::toString() or an equivalent serializer, the serialized message could contain attacker-controlled header lines. The issue can also be reached through Message::parseRequest() or Message::parseResponse() when malformed raw …
guzzlehttp/psr7 improperly interpreted malformed Host header values when constructing request URIs from inbound request data. This issue concerns inbound request parsing and server request construction. It does not require serializing a PSR-7 request, and it is not part of the normal outbound request-sending path used by guzzlehttp/guzzle. A vulnerable flow is: An attacker controls a raw HTTP request or server variable containing a Host value. The Host value contains URI …
guzzlehttp/psr7 did not reject ASCII control characters, whitespace, or DEL in first-party URI host components. The issue requires a PSR-7 request to be serialized into a raw HTTP/1.x message, for example with GuzzleHttp\Psr7\Message::toString() or an equivalent custom serializer. Creating a Uri, Request, or other PSR-7 object alone is not sufficient. The malformed host must be copied into the serialized Host header without further validation. A vulnerable flow is: An application …