unsubscribe: HTML encode undecryptable username

Otherwise, URLs can be crafted to inject HTML.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/PublicInbox/Unsubscribe.pm b/lib/PublicInbox/Unsubscribe.pm
index 95348ea3..239feea9 100644
--- a/lib/PublicInbox/Unsubscribe.pm
+++ b/lib/PublicInbox/Unsubscribe.pm
@@ -82,6 +82,7 @@ sub _user_list_addr {
                 my $errors = $env->{'psgi.errors'};
                 $errors->print("error decrypting: $u\n");
                 $errors->print("$_\n") for split("\n", $err);
+                $u = Plack::Util::encode_html($u);
                 return r($self, 400, 'Bad request', "Failed to decrypt: $u");
         }