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pam_ldap: Authentication bypass vulnerability


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200612-19 / pam_ldap
Release Date December 20, 2006
Latest Revision December 20, 2006: 01
Impact low
Exploitable remote
Package Vulnerable versions Unaffected versions Architecture(s)
sys-auth/pam_ldap < 183 >= 183 All supported architectures

Related bugreports: #153916


pam_ldap contains a vulnerability that may allow a remote user with a locked account to gain unauthorized system access.

2.  Impact Information


pam_ldap is a Pluggable Authentication Module which allows authentication against LDAP directories.


Steve Rigler discovered that pam_ldap does not correctly handle "PasswordPolicyResponse" control responses from an LDAP directory. This causes the pam_authenticate() function to always succeed, even if the previous authentication failed.


A locked user may exploit this vulnerability to bypass the LDAP authentication mechanism, possibly gaining unauthorized access to the system.

3.  Resolution Information


There is no known workaround at this time.


All pam_ldap users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-auth/pam_ldap-183"

4.  References


Page updated December 20, 2006

Summary: This is a Gentoo Linux Security Advisory

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