Add changelog entry for TLS 1.2 Finished fix

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/ChangeLog.d/tls12-check-finished-calc.txt b/ChangeLog.d/tls12-check-finished-calc.txt
new file mode 100644
index 0000000..cd52d32
--- /dev/null
+++ b/ChangeLog.d/tls12-check-finished-calc.txt
@@ -0,0 +1,6 @@
+Security
+   * Fix a vulnerability in the TLS 1.2 handshake. If memory allocation failed
+     or there was a cryptographic hardware failure when calculating the
+     Finished message, it could be calculated incorrectly. This would break
+     the security guarantees of the TLS handshake.
+     CVE-2025-27810