CVE Vulnerabilities


Cross-Site Request Forgery (CSRF)

Published: Feb 08, 2013 | Modified: Mar 08, 2013
CVSS 3.x
CVSS 2.x

Opera before 12.13 does not send CORS preflight requests in all required cases, which allows remote attackers to bypass a CSRF protection mechanism via a crafted web site that triggers a CORS request.


The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.

Affected Software

Name Vendor Start Version End Version
Opera_browser Opera * 12.12 (including)
Opera_browser Opera 12.00 (including) 12.00 (including)
Opera_browser Opera 12.00-beta (including) 12.00-beta (including)
Opera_browser Opera 12.01 (including) 12.01 (including)
Opera_browser Opera 12.02 (including) 12.02 (including)
Opera_browser Opera 12.10 (including) 12.10 (including)
Opera_browser Opera 12.10-beta (including) 12.10-beta (including)
Opera_browser Opera 12.11 (including) 12.11 (including)

Potential Mitigations

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
  • For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330]
  • Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
  • Use the “double-submitted cookie” method as described by Felten and Zeller:
  • When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user’s machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same.
  • Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult.
  • This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [REF-331]