An exploit is a piece of software, a chunk of data, or a sequence of commands that takes advantage of a bug or vulnerability to cause unintended or unanticipated behavior to occur on computer software, hardware, or something electronic (usually computerized). Such behavior frequently includes things like gaining control of a computer system, allowing privilege escalation, or a denial-of-service (DoS or related DDoS) attack.
How do exploits occur?
Although exploits can occur in a variety of ways, one common method is for exploits to be launched from malicious websites. The victim might visit such a site by accident, or they might be tricked into clicking on a link to the malicious site within a phishing email or malicious advertisements.
List of exploit database:
SecuriTeam – http://www.securiteam.com
Government Security Org – http://www.governmentsecurity.org
Secunia Advisories – http://secunia.com/advisories/ historic/
Security Reason – http://securityreason.com
XSSed XSS-Vulnerabilities – http://www.xssed.com
Security Vulnerabilities Database – http://securityvulns.com
Offensive Security Exploits Database – http://www.exploit-db.com
Indonesia Security Exploits Database – http://www.exploit-id.com
SEBUG – http://www.sebug.net
OSVDB Vulnerabilities – http://osvdb.org
National Vulnerability Database – http://nvd.nist.gov
US-CERT Vulnerability Notes – http://www.kb.cert.org/vuls
US-CERT Alerts – http://www.us-cert.gov/cas/ techalerts/