diff --git a/ChangeLog b/ChangeLog
index 0eb070212..deeaccd0c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -17,6 +17,8 @@ Security
      implementation allowed an offline 2^80 brute force attack on the
      HMAC key of a single, uninterrupted connection (with no
      resumption of the session).
+   * Fix a buffer overread in ssl_parse_server_key_exchange() that could cause
+     a crash on invalid input.
 
 Features
    * Extend PKCS#8 interface by introducing support for the entire SHA
@@ -51,6 +53,8 @@ Bugfix
      structure. Do not assume that zeroizing a context is a correct way to
      reset it. Found independently by ccli8 on Github.
    * In mbedtls_entropy_free(), properly free the message digest context.
+   * Fix a possible arithmetic overflow in ssl_parse_server_key_exchange()
+     that could cause a key exchange to fail on valid data.
 
 Changes
    * Clarified the documentation of mbedtls_ssl_setup.
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 94c521dd9..b607fda71 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2236,10 +2236,17 @@ static int ssl_parse_server_key_exchange( mbedtls_ssl_context *ssl )
         /*
          * Read signature
          */
+        if( p > end - 2 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                            MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+            return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+        }
         sig_len = ( p[0] << 8 ) | p[1];
         p += 2;
 
-        if( end != p + sig_len )
+        if( p != end - sig_len )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
             return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );