diff --git a/internal/http3/headers.go b/internal/http3/headers.go
index 02152742..a66fe1d2 100644
--- a/internal/http3/headers.go
+++ b/internal/http3/headers.go
@@ -139,6 +139,9 @@ func parseHeaders(decodeFn qpack.DecodeFunc, isRequest bool, sizeLimit int, head
 	if ds.ShouldDump() && len(hdr.Headers) > 0 {
 		ds.DumpResponseHeader([]byte("\r\n"))
 	}
+	if isRequest && (hdr.Scheme == "http" || hdr.Scheme == "https") && strings.Contains(hdr.Authority, "@") {
+		return header{}, errors.New("userinfo is not allowed in :authority")
+	}
 	hdr.ContentLength = -1
 	if len(contentLengthStr) > 0 {
 		// use ParseUint instead of ParseInt, so that parsing fails on negative values
diff --git a/internal/http3/headers_test.go b/internal/http3/headers_test.go
index e5facae5..89202e9e 100644
--- a/internal/http3/headers_test.go
+++ b/internal/http3/headers_test.go
@@ -1,10 +1,36 @@
 package http3
 
 import (
+	"io"
 	"net/http"
 	"testing"
+
+	"github.com/imroc/req/v3/internal/dump"
+	"github.com/quic-go/qpack"
 )
 
+func TestParseHeadersRejectsUserinfoInAuthority(t *testing.T) {
+	fields := []qpack.HeaderField{
+		{Name: ":method", Value: "GET"},
+		{Name: ":scheme", Value: "https"},
+		{Name: ":authority", Value: "user@example.com"},
+		{Name: ":path", Value: "/"},
+	}
+	decode := func() (qpack.HeaderField, error) {
+		if len(fields) == 0 {
+			return qpack.HeaderField{}, io.EOF
+		}
+		field := fields[0]
+		fields = fields[1:]
+		return field, nil
+	}
+
+	_, err := parseHeaders(decode, true, 1<<20, nil, dump.Dumpers{})
+	if err == nil || err.Error() != "userinfo is not allowed in :authority" {
+		t.Fatalf("got error %v, want userinfo rejection", err)
+	}
+}
+
 func TestExtractAnnouncedTrailers(t *testing.T) {
 	tests := []struct {
 		name     string
diff --git a/transfer.go b/transfer.go
index 68924d92..28a94c7b 100644
--- a/transfer.go
+++ b/transfer.go
@@ -827,19 +827,24 @@ var (
 	doubleCRLF = []byte("\r\n\r\n")
 )
 
-func seeUpcomingDoubleCRLF(r *bufio.Reader) bool {
+func seeUpcomingDoubleCRLF(r *bufio.Reader) error {
 	for peekSize := 4; ; peekSize++ {
 		// This loop stops when Peek returns an error,
 		// which it does when r's buffer has been filled.
 		buf, err := r.Peek(peekSize)
+		for i, b := range buf {
+			if b == '\n' && (i == 0 || buf[i-1] != '\r') {
+				return errors.New("http: invalid trailer")
+			}
+		}
 		if bytes.HasSuffix(buf, doubleCRLF) {
-			return true
+			return nil
 		}
 		if err != nil {
 			break
 		}
 	}
-	return false
+	return errors.New("http: suspiciously long trailer after chunked body")
 }
 
 var errTrailerEOF = errors.New("http: unexpected EOF reading trailer")
@@ -866,8 +871,8 @@ func (b *body) readTrailer() error {
 	// this bufio.textprotoReader. Instead, a hack: we iteratively Peek up
 	// to the bufio.textprotoReader's max size, looking for a double CRLF.
 	// This limits the trailer to the underlying buffer size, typically 4kB.
-	if !seeUpcomingDoubleCRLF(b.r) {
-		return errors.New("http: suspiciously long trailer after chunked body")
+	if err := seeUpcomingDoubleCRLF(b.r); err != nil {
+		return err
 	}
 
 	hdr, err := textproto.NewReader(b.r).ReadMIMEHeader()
diff --git a/transfer_test.go b/transfer_test.go
index b8c203c2..cc258803 100644
--- a/transfer_test.go
+++ b/transfer_test.go
@@ -2,8 +2,12 @@ package req
 
 import (
 	"bufio"
+	"fmt"
+	"io"
+	"net"
 	"net/http"
 	"strings"
+	"sync/atomic"
 	"testing"
 )
 
@@ -26,3 +30,63 @@ func TestReadTransferClosesResponseWithTransferEncodingAndContentLength(t *testi
 		t.Fatal("response with both Transfer-Encoding and Content-Length did not set Close")
 	}
 }
+
+func TestResponseWithBareLFInTrailerClosesConnection(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+
+	var connections, requests atomic.Int32
+	go func() {
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			connections.Add(1)
+			go func() {
+				defer conn.Close()
+				r := bufio.NewReader(conn)
+				for {
+					req, err := http.ReadRequest(r)
+					if err != nil {
+						return
+					}
+					req.Body.Close()
+					if requests.Add(1) == 1 {
+						fmt.Fprint(conn, "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\nTrailer: X-One, X-Two\r\n\r\n0\r\nX-One: a\nX-Two: b\r\n\r\n")
+					} else {
+						fmt.Fprint(conn, "HTTP/1.1 200 OK\r\nContent-Length: 2\r\n\r\nok")
+					}
+				}
+			}()
+		}
+	}()
+
+	tr := NewTransport()
+	defer tr.CloseIdleConnections()
+	client := &http.Client{Transport: tr}
+	resp, err := client.Get("http://" + ln.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = io.ReadAll(resp.Body)
+	resp.Body.Close()
+	if err == nil || err.Error() != "http: invalid trailer" {
+		t.Fatalf("got body read error %v, want http: invalid trailer", err)
+	}
+
+	resp, err = client.Get("http://" + ln.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if _, err := io.ReadAll(resp.Body); err != nil {
+		t.Fatal(err)
+	}
+	if got := connections.Load(); got != 2 {
+		t.Fatalf("got %d connections, want 2; invalid trailer connection was reused", got)
+	}
+}