diff --git a/DESCRIPTION.md b/DESCRIPTION.md
index ad9f2156d1..02aacc0186 100644
--- a/DESCRIPTION.md
+++ b/DESCRIPTION.md
@@ -7,6 +7,9 @@ https://docs.snowflake.com/
 Source code is also available at: https://github.com/snowflakedb/snowflake-connector-python
 
 # Release Notes
+- v4.6.1(TBD)
+  - Fixed SSL hostname mismatch when using the async connector with account names containing underscores (#1839).
+
 - v4.6.0(May 28,2026)
   - Dropped support for Python 3.9. The minimum supported version is now Python 3.10.
   - Fixed sdist to only install the minicore binary matching the current platform (SNOW-3526469). Previous 4.x releases copied every platform's minicore `.so`/`.dylib`/`.dll` into the install prefix, breaking downstream packagers (e.g. Homebrew) whose audits reject foreign-arch binaries.
diff --git a/src/snowflake/connector/util_text.py b/src/snowflake/connector/util_text.py
index 6a62f422b8..41622aa43e 100644
--- a/src/snowflake/connector/util_text.py
+++ b/src/snowflake/connector/util_text.py
@@ -306,6 +306,8 @@ def _concatenate_statements(
 
 def construct_hostname(region: str | None, account: str) -> str:
     """Constructs hostname from region and account."""
+    # RFC 952: underscores are not valid in hostnames
+    account = account.replace("_", "-")
 
     def _is_china_region(r: str) -> bool:
         # This is consistent with the Go driver: