diff --git a/src/core/dbus-execute.c b/src/core/dbus-execute.c
index aea9fbb304..2329762f16 100644
--- a/src/core/dbus-execute.c
+++ b/src/core/dbus-execute.c
@@ -3456,6 +3456,9 @@ int bus_exec_context_set_transient_property(
                 if (r < 0)
                         return r;
 
+                if (strv_length(l) > ENVIRONMENT_ASSIGNMENTS_MAX)
+                        return sd_bus_error_set(reterr_error, SD_BUS_ERROR_LIMITS_EXCEEDED,
+                                                "Too many environment assignments.");
                 if (!strv_env_is_valid(l))
                         return sd_bus_error_set(reterr_error, SD_BUS_ERROR_INVALID_ARGS, "Invalid environment block.");
 
@@ -3490,6 +3493,9 @@ int bus_exec_context_set_transient_property(
                 if (r < 0)
                         return r;
 
+                if (strv_length(l) > ENVIRONMENT_ASSIGNMENTS_MAX)
+                        return sd_bus_error_set(reterr_error, SD_BUS_ERROR_LIMITS_EXCEEDED,
+                                                "Too many environment variable names or assignments.");
                 if (!strv_env_name_or_assignment_is_valid(l))
                         return sd_bus_error_set(reterr_error, SD_BUS_ERROR_INVALID_ARGS, "Invalid UnsetEnvironment= list.");
 
@@ -3642,6 +3648,9 @@ int bus_exec_context_set_transient_property(
                 if (r < 0)
                         return r;
 
+                if (strv_length(l) > ENVIRONMENT_ASSIGNMENTS_MAX)
+                        return sd_bus_error_set(reterr_error, SD_BUS_ERROR_LIMITS_EXCEEDED,
+                                                "Too many environment variable names.");
                 if (!strv_env_name_is_valid(l))
                         return sd_bus_error_set(reterr_error, SD_BUS_ERROR_INVALID_ARGS, "Invalid PassEnvironment= block.");