diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index cc3e054eef..9244dc5e32 100644
--- a/docs/KNOWN_BUGS
+++ b/docs/KNOWN_BUGS
@@ -16,6 +16,7 @@ problems may have been fixed or changed somewhat since this was written.
  1.5 Expect-100 meets 417
 
  2. TLS
+ 2.1 IMAPS connection fails with rustls error
  2.3 Unable to use PKCS12 certificate with Secure Transport
  2.4 Secure Transport will not import PKCS#12 client certificates without a password
  2.5 Client cert handling with Issuer DN differs between backends
@@ -136,6 +137,10 @@ problems may have been fixed or changed somewhat since this was written.
 
 2. TLS
 
+2.1 IMAPS connection fails with rustls error
+
+ https://github.com/curl/curl/issues/10457
+
 2.3 Unable to use PKCS12 certificate with Secure Transport
 
  See https://github.com/curl/curl/issues/5403