Update CHANGES/NEWS to mention the HollowByte fix

Add a previously missing CHANGES.md/NEWS.md entry for the Hollowbyte fix.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Norbert Pocs <norbertp@openssl.org>
MergeDate: Wed Jul 29 09:15:32 2026
(Merged from https://github.com/openssl/openssl/pull/32039)

diff --git a/CHANGES.md b/CHANGES.md
index 8d507e4f32e1aa56e311308fa84fe3a9fd478de2..cf726e8be43362f59313ef68081ae3fa60ea8428 100644 (file)
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -302,6 +302,20 @@ OpenSSL 4.0
 
 ### Changes between 4.0.0 and 4.0.1 [9 Jun 2026]
 
+ * Fixed excessive allocation of the handshake message buffer (aka HollowByte)
+
+   Previously, we would allocate a buffer large enough to hold the full size of
+   an incoming handshake message as advertised by the peer. This could be quite
+   large (although it is bounded, e.g. for ClientHello this is approximately
+   128 KiB). If the peer then fails to send the full handshake message, then the
+   endpoint is left waiting for the remainder of the message to arrive and the
+   memory is still allocated (i.e. a Slowloris attack). To prevent this, we
+   incrementally grow the buffer as we receive the data.
+
+   This issue was reported by Okta Red Team.
+
+   *Matt Caswell*
+
  * Fixed heap use-after-free in `PKCS7_verify()`.
 
    Severity: High

diff --git a/NEWS.md b/NEWS.md
index 239f195de052e7160c05c0f40397556fd2704b87..5b446f8d45eef49a159be8c80fa06f90b02bc1bd 100644 (file)
--- a/NEWS.md
+++ b/NEWS.md
@@ -100,6 +100,8 @@ This release incorporates the following bug fixes and mitigations:
     and AES-SIV modes.
     ([CVE-2026-45446])
 
+  * Fixed excessive allocation of the handshake message buffer (aka HollowByte)
+
   * Fixed a regression introduced in 4.0.0 that led to a `openssl pkey`
     command crash when it was invoked to encrypt a private key with password
     being provided interactively.