doc: release-notes: notify about Mbed TLS version upgrade

Add a note about Mbed TLS version upgrade from 3.6.4 to 3.6.5.
Update also the CVE list accordingly.

Signed-off-by: Valerio Setti <vsetti@baylibre.com>

Author: valeriosetti

doc/releases/release-notes-4.3.rst

@@ -87,6 +87,10 @@ The following CVEs are addressed by this release:
 * :cve:`2025-9557`: Under embargo until 2025-11-24
 * :cve:`2025-9558`: Under embargo until 2025-11-24
 * :cve:`2025-12035`: Under embargo until 2025-12-13
+* :cve:`2025-59438` `Padding oracle through timing of cipher error reporting
+  <https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-10-invalid-padding-error/>`_
+* :cve:`2025-54764` `Side channel in RSA key generation and operations (SSBleed, M-Step)
+  <https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-10-ssbleed-mstep/>`_
 
 More detailed information can be found in:
 https://docs.zephyrproject.org/latest/security/vulnerabilities.html
@@ -1243,6 +1247,11 @@ Libraries / Subsystems
     :kconfig:option:`CONFIG_PSA_CRYPTO_PROVIDER_CUSTOM` is also added to allow end users to
     provide a custom solution.
 
+  * Updated from version 3.6.4 to version 3.6.5. Release notes for this release can be found at the
+    following link:
+
+    * https://github.com/Mbed-TLS/mbedtls/releases/tag/mbedtls-3.6.5
+
 * Secure storage
 
   * The experimental status has been removed. (:github:`96483`)