Add CHANGES.md and NEWS.md entries for CVE-2023-2975

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from #21384)

(cherry picked from commit 1e398be)

CHANGES.md

@@ -30,7 +30,25 @@ breaking changes, and mappings for the large list of deprecated functions.
 
 ### Changes between 3.0.9 and 3.0.10 [xx XXX xxxx]
 
- * none yet
+ * Do not ignore empty associated data entries with AES-SIV.
+
+   The AES-SIV algorithm allows for authentication of multiple associated
+   data entries along with the encryption. To authenticate empty data the
+   application has to call `EVP_EncryptUpdate()` (or `EVP_CipherUpdate()`)
+   with NULL pointer as the output buffer and 0 as the input buffer length.
+   The AES-SIV implementation in OpenSSL just returns success for such call
+   instead of performing the associated data authentication operation.
+   The empty data thus will not be authenticated. ([CVE-2023-2975])
+
+   Thanks to Juerg Wullschleger (Google) for discovering the issue.
+
+   The fix changes the authentication tag value and the ciphertext for
+   applications that use empty associated data entries with AES-SIV.
+   To decrypt data encrypted with previous versions of OpenSSL the application
+   has to skip calls to `EVP_DecryptUpdate()` for empty associated data
+   entries.
+
+   *Tomas Mraz*
 
 ### Changes between 3.0.8 and 3.0.9 [30 May 2023]
 
@@ -19654,6 +19672,7 @@ ndif
 
 <!-- Links -->
 
+[CVE-2023-2975]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-2975
 [RFC 2578 (STD 58), section 3.5]: https://datatracker.ietf.org/doc/html/rfc2578#section-3.5
 [CVE-2023-2650]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-2650
 [CVE-2023-1255]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-1255

NEWS.md

@@ -20,7 +20,7 @@ OpenSSL 3.0
 
 ### Major changes between OpenSSL 3.0.9 and OpenSSL 3.0.10 [under development]
 
-  * none
+  * Do not ignore empty associated data entries with AES-SIV ([CVE-2023-2975])
 
 ### Major changes between OpenSSL 3.0.8 and OpenSSL 3.0.9 [30 May 2023]
 
@@ -1446,6 +1446,7 @@ OpenSSL 0.9.x
 
 <!-- Links -->
 
+[CVE-2023-2975]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-2975
 [CVE-2023-2650]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-2650
 [CVE-2023-1255]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-1255
 [CVE-2023-0466]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-0466