The printer friendly version functionality in the Book module in Drupal 6.x before 6.28 and 7.x before 7.19 does not properly restrict access to node that are part of a book outline, which allows remote authenticated users with the "access printer-friendly version" permission to read node titles and possibly node content via unspecified vectors.
https://exchange.xforce.ibmcloud.com/vulnerabilities/81380
https://drupal.org/SA-CORE-2013-001
http://www.debian.org/security/2013/dsa-2776
http://secunia.com/advisories/51717
http://seclists.org/oss-sec/2013/q1/211