diff --git a/NEWS.md b/NEWS.md
index 598be714e5..99a2a36da8 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -74,7 +74,7 @@ The following bundled gems are updated.
 * minitest 5.25.5
 * test-unit 3.6.8
 * rexml 3.4.1
-* net-imap 0.5.6
+* net-imap 0.5.7
 * net-smtp 0.5.1
 * rbs 3.9.2
 * bigdecimal 3.1.9
diff --git a/gems/bundled_gems b/gems/bundled_gems
index d02946cd6b..408c994e81 100644
--- a/gems/bundled_gems
+++ b/gems/bundled_gems
@@ -13,7 +13,7 @@ test-unit           3.6.8   https://github.com/test-unit/test-unit
 rexml               3.4.1   https://github.com/ruby/rexml
 rss                 0.3.1   https://github.com/ruby/rss
 net-ftp             0.3.8   https://github.com/ruby/net-ftp
-net-imap            0.5.6   https://github.com/ruby/net-imap
+net-imap            0.5.7   https://github.com/ruby/net-imap
 net-pop             0.1.2   https://github.com/ruby/net-pop
 net-smtp            0.5.1   https://github.com/ruby/net-smtp
 matrix              0.4.2   https://github.com/ruby/matrix