Explanation/Reference:
Allowing objects to be used sequentially by multiple users without a refresh of the objects can lead to disclosure of residual data. It is important that steps be taken to eliminate the chance for the disclosure of residual data.
Object reuse refers to the allocation or reallocation of system resources to a user or, more appropriately, to an application or process. Applications and services on a computer system may create or use objects in memory and in storage to perform programmatic functions. In some cases, it is necessary to share these resources between various system applications. However, some objects may be employed by an application to perform privileged tasks on behalf of an authorized user or upstream application. If object usage is not controlled or the data in those objects is not erased after use, they may become available to unauthorized users or processes.
Disclosure of residual data and Unauthorized obtaining of a privileged execution state are both a problem with shared memory and resources. Not clearing the heap/stack can result in residual data and may also allow the user to step on somebody's session if the security token/identify was maintained in that space.
This is generally more malicious and intentional than accidental though. The MOST common issue would be Disclosure of residual data.
The following answers are incorrect:
Unauthorized obtaining of a privileged execution state. Is incorrect because this is not a problem with Object Reuse.
Data leakage through covert channels. Is incorrect because it is not the best answer. A covert channel is a communication path. Data leakage would not be a problem created by Object Reuse. In computer security, a covert channel is a type of computer security attack that creates a capability to transfer information objects between processes that are not supposed to be allowed to communicate by the computer security policy. The term, originated in 1973 by Lampson is defined as "(channels) not intended for information transfer at all, such as the service program's effect on system load." to distinguish it from Legitimate channels that are subjected to access controls by COMPUSEC.
Denial of service through a deadly embrace. Is incorrect because it is only a detractor.
References:
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 4174-4179). Auerbach Publications. Kindle Edition.
and
https://www.fas.org/irp/nsa/rainbow/tg018.htm
and
http://en.wikipedia.org/wiki/Covert_channel

Communications devices must operate at the same speed to communicate.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 100.

Packet filtering is used in the first generation of firewalls and does not keep
track of the state of a connection. Stateful packet filtering does.
Source: WALLHOFF, John, CISSP Summary 2002, April 2002, CBK#2
Telecommunications and Network Security (page 6)

Actions to be performed in case of a disaster are not normally part of an
information security policy but part of a Disaster Recovery Plan (DRP).
Only personnel implicated in the plan should have a copy of the Disaster Recovery Plan
whereas everyone should be aware of the contents of the organization's information
security policy.
Source: ALLEN, Julia H., The CERT Guide to System and Network Security Practices,
Addison-Wesley, 2001, Appendix B, Practice-Level Policy Considerations (page 398).

A hash algorithm (alternatively, hash "function") takes binary data, called the message, and produces a condensed representation, called the message digest. A cryptographic hash algorithm is a hash algorithm that is designed to achieve certain security properties. The Federal Information Processing Standard 180-3, Secure Hash Standard, specifies five cryptographic hash algorithms - SHA-1, SHA-224, SHA-256, SHA384, and SHA-512 for federal use in the US; the standard was also widely adopted by the information technology industry and commercial companies.
The MD5 Message-Digest Algorithm is a widely used cryptographic hash function that produces a 128-bit (16-byte) hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check data integrity. MD5 was designed by Ron Rivest in 1991 to replace an earlier hash function, MD4. An MD5 hash is typically expressed as a 32-digit hexadecimal number.
However, it has since been shown that MD5 is not collision resistant; as such, MD5 is not suitable for applications like SSL certificates or digital signatures that rely on this property. In 1996, a flaw was found with the design of MD5, and while it was not a clearly fatal weakness, cryptographers began recommending the use of other algorithms, such as SHA1 - which has since been found also to be vulnerable. In 2004, more serious flaws were discovered in MD5, making further use of the algorithm for security purposes questionable specifically, a group of researchers described how to create a pair of files that share the same MD5 checksum. Further advances were made in breaking MD5 in 2005, 2006, and 2007. In December 2008, a group of researchers used this technique to fake SSL certificate validity, and US-CERT now says that MD5 "should be considered cryptographically broken and unsuitable for further use." and most U.S. government applications now require the SHA-2 family of hash functions.
NIST CRYPTOGRAPHIC HASH PROJECT NIST announced a public competition in a Federal Register Notice on November 2, 2007 to develop a new cryptographic hash algorithm, called SHA-3, for standardization. The competition was NIST's response to advances made in the cryptanalysis of hash algorithms.
NIST received sixty-four entries from cryptographers around the world by October 31, 2008, and selected fifty-one first-round candidates in December 2008, fourteen second-round candidates in July 2009, and five finalists - BLAKE, Grostl, JH, Keccak and Skein, in December 2010 to advance to the third and final round of the competition.
Throughout the competition, the cryptographic community has provided an enormous amount of feedback. Most of the comments were sent to NIST and a public hash forum; in addition, many of the cryptanalysis and performance studies were published as papers in major cryptographic conferences or leading cryptographic journals. NIST also hosted a SHA-3 candidate conference in each round to obtain public feedback. Based on the public comments and internal review of the candidates, NIST announced Keccak as the winner of the SHA-3 Cryptographic Hash Algorithm Competition on October 2, 2012, and ended the five-year competition.
Reference:
Tipton, Harold, et. al., Officical (ISC)2 Guide to the CISSP CBK, 2007 edition, page 261.
and
https://secure.wikimedia.org/wikipedia/en/wiki/Md5
and http://csrc.nist.gov/groups/ST/hash/sha-3/index.html