diff --git a/server/certificates/certificates.go b/server/certificates/certificates.go
index 8882e02..8d9f704 100644
--- a/server/certificates/certificates.go
+++ b/server/certificates/certificates.go
@@ -34,6 +34,7 @@ func TLSConfig(mainDomainSuffix string,
 	keyCache, challengeCache, dnsLookupCache, canonicalDomainCache cache.ICache,
 	certDB database.CertDB,
 	noDNS01 bool,
+	rawDomain string,
 ) *tls.Config {
 	return &tls.Config{
 		// check DNS name & get certificate from Let's Encrypt
@@ -68,8 +69,17 @@ func TLSConfig(mainDomainSuffix string,
 
 			if strings.HasSuffix(domain, mainDomainSuffix) || strings.EqualFold(domain, mainDomainSuffix[1:]) {
 				if noDNS01 {
-					//TODO check if the domain is served to avoid DOSing ourseflve
-					mayObtainCert = true
+					// Limit the domains allowed to request a certificate to pages-server domains
+					// and domains for an existing user of org
+					if !strings.EqualFold(domain, mainDomainSuffix[1:]) && !strings.EqualFold(domain, rawDomain) {
+						targetOwner := strings.TrimSuffix(domain, mainDomainSuffix)
+						owner_exist, err := giteaClient.GiteaCheckIfOwnerExists(targetOwner)
+						mayObtainCert = owner_exist
+						if err != nil {
+							log.Error().Err(err).Msgf("Failed to check '%s' existance on the forge: %s", targetOwner, err)
+							mayObtainCert = false
+						}
+					}
 				} else {
 					// deliver default certificate for the main domain (*.codeberg.page)
 					domain = mainDomainSuffix
diff --git a/server/gitea/cache.go b/server/gitea/cache.go
index 267c3d8..fcd4076 100644
--- a/server/gitea/cache.go
+++ b/server/gitea/cache.go
@@ -26,6 +26,9 @@ const (
 	// TODO: move as option into cache interface
 	fileCacheTimeout = 5 * time.Minute
 
+	// ownerExistanceCacheTimeout specifies the timeout for the existance of a repo/org
+	ownerExistanceCacheTimeout = 5 * time.Minute
+
 	// fileCacheSizeLimit limits the maximum file size that will be cached, and is set to 1 MB by default.
 	fileCacheSizeLimit = int64(1000 * 1000)
 )
diff --git a/server/gitea/client.go b/server/gitea/client.go
index 42cf065..320669d 100644
--- a/server/gitea/client.go
+++ b/server/gitea/client.go
@@ -28,6 +28,7 @@ const (
 	branchTimestampCacheKeyPrefix = "branchTime"
 	defaultBranchCacheKeyPrefix   = "defaultBranch"
 	rawContentCacheKeyPrefix      = "rawContent"
+	ownerExistance                = "ownerExist"
 
 	// pages server
 	PagesCacheIndicatorHeader = "X-Pages-Cache"
@@ -263,6 +264,38 @@ func (client *Client) GiteaGetRepoDefaultBranch(repoOwner, repoName string) (str
 	return branch, nil
 }
 
+func (client *Client) GiteaCheckIfOwnerExists(owner string) (bool, error) {
+	cacheKey := fmt.Sprintf("%s/%s", ownerExistance, owner)
+
+	if exist, ok := client.responseCache.Get(cacheKey); ok && exist != nil {
+		return exist.(bool), nil
+	}
+
+	_, resp, err := client.sdkClient.GetUserInfo(owner)
+	if resp.StatusCode == http.StatusOK && err == nil {
+		if err := client.responseCache.Set(cacheKey, true, ownerExistanceCacheTimeout); err != nil {
+			log.Error().Err(err).Msg("[cache] error on cache write")
+		}
+		return true, nil
+	} else if resp.StatusCode != http.StatusNotFound {
+		return false, err
+	}
+
+	_, resp, err = client.sdkClient.GetOrg(owner)
+	if resp.StatusCode == http.StatusOK && err == nil {
+		if err := client.responseCache.Set(cacheKey, true, ownerExistanceCacheTimeout); err != nil {
+			log.Error().Err(err).Msg("[cache] error on cache write")
+		}
+		return true, nil
+	} else if resp.StatusCode != http.StatusNotFound {
+		return false, err
+	}
+	if err := client.responseCache.Set(cacheKey, false, ownerExistanceCacheTimeout); err != nil {
+		log.Error().Err(err).Msg("[cache] error on cache write")
+	}
+	return false, nil
+}
+
 func (client *Client) getMimeTypeByExtension(resource string) string {
 	mimeType := mime.TypeByExtension(path.Ext(resource))
 	mimeTypeSplit := strings.SplitN(mimeType, ";", 2)
diff --git a/server/startup.go b/server/startup.go
index 0f2db60..149a07d 100644
--- a/server/startup.go
+++ b/server/startup.go
@@ -111,6 +111,7 @@ func Serve(ctx *cli.Context) error {
 		keyCache, challengeCache, dnsLookupCache, canonicalDomainCache,
 		certDB,
 		cfg.ACME.NoDNS01,
+		cfg.Server.RawDomain,
 	))
 
 	interval := 12 * time.Hour