diff --git a/models/activities/action.go b/models/activities/action.go
index b6c816f096..dd67b98242 100644
--- a/models/activities/action.go
+++ b/models/activities/action.go
@@ -250,6 +250,9 @@ func (a *Action) GetActDisplayNameTitle(ctx context.Context) string {
 // GetRepoUserName returns the name of the action repository owner.
 func (a *Action) GetRepoUserName(ctx context.Context) string {
 	a.loadRepo(ctx)
+	if a.Repo == nil {
+		return "(non-existing-repo)"
+	}
 	return a.Repo.OwnerName
 }
 
@@ -262,6 +265,9 @@ func (a *Action) ShortRepoUserName(ctx context.Context) string {
 // GetRepoName returns the name of the action repository.
 func (a *Action) GetRepoName(ctx context.Context) string {
 	a.loadRepo(ctx)
+	if a.Repo == nil {
+		return "(non-existing-repo)"
+	}
 	return a.Repo.Name
 }
 
diff --git a/modules/markup/asciicast/asciicast.go b/modules/markup/asciicast/asciicast.go
index 0678062340..873029c1bd 100644
--- a/modules/markup/asciicast/asciicast.go
+++ b/modules/markup/asciicast/asciicast.go
@@ -39,7 +39,7 @@ const (
 // SanitizerRules implements markup.Renderer
 func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
 	return []setting.MarkupSanitizerRule{
-		{Element: "div", AllowAttr: "class", Regexp: regexp.MustCompile(playerClassName)},
+		{Element: "div", AllowAttr: "class", Regexp: regexp.MustCompile("^" + playerClassName + "$")},
 		{Element: "div", AllowAttr: playerSrcAttr},
 	}
 }
diff --git a/modules/markup/csv/csv.go b/modules/markup/csv/csv.go
index 3d952b0de4..092eec7098 100644
--- a/modules/markup/csv/csv.go
+++ b/modules/markup/csv/csv.go
@@ -37,9 +37,9 @@ func (Renderer) Extensions() []string {
 // SanitizerRules implements markup.Renderer
 func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
 	return []setting.MarkupSanitizerRule{
-		{Element: "table", AllowAttr: "class", Regexp: regexp.MustCompile(`data-table`)},
-		{Element: "th", AllowAttr: "class", Regexp: regexp.MustCompile(`line-num`)},
-		{Element: "td", AllowAttr: "class", Regexp: regexp.MustCompile(`line-num`)},
+		{Element: "table", AllowAttr: "class", Regexp: regexp.MustCompile(`^data-table$`)},
+		{Element: "th", AllowAttr: "class", Regexp: regexp.MustCompile(`^line-num$`)},
+		{Element: "td", AllowAttr: "class", Regexp: regexp.MustCompile(`^line-num$`)},
 	}
 }
 
diff --git a/release-notes/5998.md b/release-notes/5998.md
new file mode 100644
index 0000000000..b1b7d56d08
--- /dev/null
+++ b/release-notes/5998.md
@@ -0,0 +1,4 @@
+fix(security): [commit](https://codeberg.org/forgejo/forgejo/commit/53c546951115d9e269a2778f90e43b0cb413eab6) Fix and refactor markdown rendering
+fix: [commit](https://codeberg.org/forgejo/forgejo/commit/6ac04b8c7dcedb9c6d994bb2a8cd37580394d9dd) Fix oauth2 error handle not return immediately
+fix: [commit](https://codeberg.org/forgejo/forgejo/commit/9f05c76b7b84f3cfafd4de22f5f18b87e4c79775) Fix nil panic if repo doesn't exist
+fix: [commit](https://codeberg.org/forgejo/forgejo/commit/8cec637d08542535d1dc9689c22943cd3ffe1c45) Disable Oauth check if oauth disabled
diff --git a/routers/web/auth/oauth.go b/routers/web/auth/oauth.go
index ee08b514b1..651c9fb474 100644
--- a/routers/web/auth/oauth.go
+++ b/routers/web/auth/oauth.go
@@ -1013,6 +1013,8 @@ func SignInOAuthCallback(ctx *context.Context) {
 		}
 		if err, ok := err.(*go_oauth2.RetrieveError); ok {
 			ctx.Flash.Error("OAuth2 RetrieveError: "+err.Error(), true)
+			ctx.Redirect(setting.AppSubURL + "/user/login")
+			return
 		}
 		ctx.ServerError("UserSignIn", err)
 		return
diff --git a/routers/web/web.go b/routers/web/web.go
index b93192143e..ab73ef9b36 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -327,6 +327,13 @@ func registerRoutes(m *web.Route) {
 		}
 	}
 
+	oauth2Enabled := func(ctx *context.Context) {
+		if !setting.OAuth2.Enabled {
+			ctx.Error(http.StatusForbidden)
+			return
+		}
+	}
+
 	reqMilestonesDashboardPageEnabled := func(ctx *context.Context) {
 		if !setting.Service.ShowMilestonesDashboardPage {
 			ctx.Error(http.StatusForbidden)
@@ -516,16 +523,18 @@ func registerRoutes(m *web.Route) {
 	m.Any("/user/events", routing.MarkLongPolling, events.Events)
 
 	m.Group("/login/oauth", func() {
-		m.Get("/authorize", web.Bind(forms.AuthorizationForm{}), auth.AuthorizeOAuth)
-		m.Post("/grant", web.Bind(forms.GrantApplicationForm{}), auth.GrantApplicationOAuth)
-		// TODO manage redirection
-		m.Post("/authorize", web.Bind(forms.AuthorizationForm{}), auth.AuthorizeOAuth)
-	}, ignSignInAndCsrf, reqSignIn)
+		m.Group("", func() {
+			m.Get("/authorize", web.Bind(forms.AuthorizationForm{}), auth.AuthorizeOAuth)
+			m.Post("/grant", web.Bind(forms.GrantApplicationForm{}), auth.GrantApplicationOAuth)
+			// TODO manage redirection
+			m.Post("/authorize", web.Bind(forms.AuthorizationForm{}), auth.AuthorizeOAuth)
+		}, ignSignInAndCsrf, reqSignIn)
 
-	m.Methods("GET, OPTIONS", "/login/oauth/userinfo", optionsCorsHandler(), ignSignInAndCsrf, auth.InfoOAuth)
-	m.Methods("POST, OPTIONS", "/login/oauth/access_token", optionsCorsHandler(), web.Bind(forms.AccessTokenForm{}), ignSignInAndCsrf, auth.AccessTokenOAuth)
-	m.Methods("GET, OPTIONS", "/login/oauth/keys", optionsCorsHandler(), ignSignInAndCsrf, auth.OIDCKeys)
-	m.Methods("POST, OPTIONS", "/login/oauth/introspect", optionsCorsHandler(), web.Bind(forms.IntrospectTokenForm{}), ignSignInAndCsrf, auth.IntrospectOAuth)
+		m.Methods("GET, OPTIONS", "/userinfo", optionsCorsHandler(), ignSignInAndCsrf, auth.InfoOAuth)
+		m.Methods("POST, OPTIONS", "/access_token", optionsCorsHandler(), web.Bind(forms.AccessTokenForm{}), ignSignInAndCsrf, auth.AccessTokenOAuth)
+		m.Methods("GET, OPTIONS", "/keys", optionsCorsHandler(), ignSignInAndCsrf, auth.OIDCKeys)
+		m.Methods("POST, OPTIONS", "/introspect", optionsCorsHandler(), web.Bind(forms.IntrospectTokenForm{}), ignSignInAndCsrf, auth.IntrospectOAuth)
+	}, oauth2Enabled)
 
 	m.Group("/user/settings", func() {
 		m.Get("", user_setting.Profile)
@@ -567,17 +576,24 @@ func registerRoutes(m *web.Route) {
 			}, openIDSignInEnabled)
 			m.Post("/account_link", linkAccountEnabled, security.DeleteAccountLink)
 		})
-		m.Group("/applications/oauth2", func() {
-			m.Get("/{id}", user_setting.OAuth2ApplicationShow)
-			m.Post("/{id}", web.Bind(forms.EditOAuth2ApplicationForm{}), user_setting.OAuthApplicationsEdit)
-			m.Post("/{id}/regenerate_secret", user_setting.OAuthApplicationsRegenerateSecret)
-			m.Post("", web.Bind(forms.EditOAuth2ApplicationForm{}), user_setting.OAuthApplicationsPost)
-			m.Post("/{id}/delete", user_setting.DeleteOAuth2Application)
-			m.Post("/{id}/revoke/{grantId}", user_setting.RevokeOAuth2Grant)
+
+		m.Group("/applications", func() {
+			// oauth2 applications
+			m.Group("/oauth2", func() {
+				m.Get("/{id}", user_setting.OAuth2ApplicationShow)
+				m.Post("/{id}", web.Bind(forms.EditOAuth2ApplicationForm{}), user_setting.OAuthApplicationsEdit)
+				m.Post("/{id}/regenerate_secret", user_setting.OAuthApplicationsRegenerateSecret)
+				m.Post("", web.Bind(forms.EditOAuth2ApplicationForm{}), user_setting.OAuthApplicationsPost)
+				m.Post("/{id}/delete", user_setting.DeleteOAuth2Application)
+				m.Post("/{id}/revoke/{grantId}", user_setting.RevokeOAuth2Grant)
+			}, oauth2Enabled)
+
+			// access token applications
+			m.Combo("").Get(user_setting.Applications).
+				Post(web.Bind(forms.NewAccessTokenForm{}), user_setting.ApplicationsPost)
+			m.Post("/delete", user_setting.DeleteApplication)
 		})
-		m.Combo("/applications").Get(user_setting.Applications).
-			Post(web.Bind(forms.NewAccessTokenForm{}), user_setting.ApplicationsPost)
-		m.Post("/applications/delete", user_setting.DeleteApplication)
+
 		m.Combo("/keys").Get(user_setting.Keys).
 			Post(web.Bind(forms.AddKeyForm{}), user_setting.KeysPost)
 		m.Post("/keys/delete", user_setting.DeleteKey)
@@ -755,12 +771,7 @@ func registerRoutes(m *web.Route) {
 				m.Post("/regenerate_secret", admin.ApplicationsRegenerateSecret)
 				m.Post("/delete", admin.DeleteApplication)
 			})
-		}, func(ctx *context.Context) {
-			if !setting.OAuth2.Enabled {
-				ctx.Error(http.StatusForbidden)
-				return
-			}
-		})
+		}, oauth2Enabled)
 
 		m.Group("/actions", func() {
 			m.Get("", admin.RedirectToDefaultSetting)
@@ -883,12 +894,7 @@ func registerRoutes(m *web.Route) {
 						m.Post("/regenerate_secret", org.OAuthApplicationsRegenerateSecret)
 						m.Post("/delete", org.DeleteOAuth2Application)
 					})
-				}, func(ctx *context.Context) {
-					if !setting.OAuth2.Enabled {
-						ctx.Error(http.StatusForbidden)
-						return
-					}
-				})
+				}, oauth2Enabled)
 
 				m.Group("/hooks", func() {
 					m.Get("", org.Webhooks)
diff --git a/services/auth/oauth2.go b/services/auth/oauth2.go
index 6a63c62796..8b625a193e 100644
--- a/services/auth/oauth2.go
+++ b/services/auth/oauth2.go
@@ -68,6 +68,9 @@ func grantAdditionalScopes(grantScopes string) string {
 // CheckOAuthAccessToken returns uid of user from oauth token
 // + non default openid scopes requested
 func CheckOAuthAccessToken(ctx context.Context, accessToken string) (int64, string) {
+	if !setting.OAuth2.Enabled {
+		return 0, ""
+	}
 	// JWT tokens require a "."
 	if !strings.Contains(accessToken, ".") {
 		return 0, ""