Allow DB user to change their password

Question

Greetings,
DAD authenticated access to HTMLDB 2.0 on 10gR1 on hpux.
I have built a "account" page where among other things the users can change their passwords, I have built the page over anonymous PL/SQL (below). When a DAD authenticated user runs the page via HTMLDB, they get
ORA-01031: insufficient privileges
Error. Yet if I copy the PL_SQL as is into sqlplus and bind it... it works like a charm. Any ideas?
the PL/SQL
DECLARE
BEGIN
if (:P17_NEW_PASSWORD_1 IS NOT NULL) AND (:P17_NEW_PASSWORD_2 IS NOT NULL) AND (:P17_OLD_PASSWORD IS NOT NULL) THEN
if :P17_NEW_PASSWORD_1 != :P17_NEW_PASSWORD_2 then
raise_application_error(-20300,'New passwords do not match');
end if;
execute immediate 'alter user '||user||' identified by '||:P17_NEW_PASSWORD_1||' replace '||:p17_old_password;
htp.p('Password Changed Successfully');
end if; --passwords not null
exception when others then
htp.p('Error changing password:'||sqlerrm);
null;
end;

Answer 1

The application parsing schema (owner) needs ALTER USER privilege. It probably works in SQL*Plus because that schema has obtained the privilege through a role.
Scott