A vulnerability in mod_auth_shadow, an Apache module that lets users perform HTTP authentication against /etc/shadow, has been discovered. The module runs for all locations that use the 'require group' directive which would bypass access restrictions controlled by another authorisation mechanism, such as AuthGroupFile file, if the username is listed in the password file and in the gshadow file in the proper group and the supplied password matches against the one in the shadow file.
This update requires an explicit "AuthShadow on" statement if website authentication should be checked against /etc/shadow.
For the old stable distribution (woody) this problem has been fixed in version 1.3-3.1woody.2.
For the stable distribution (sarge) this problem has been fixed in version 1.4-1sarge1.
For the unstable distribution (sid) this problem has been fixed in version 1.4-2.
We recommend that you upgrade your libapache-mod-auth-shadow package.