Ruby OpenID (aka ruby-openid) through 2.8.0 has a remotely exploitable flaw. This library is used by Rails web applications to integrate with OpenID Providers. Severity can range from medium to critical, depending on how a web application developer chose to employ the ruby-openid library. Developers who based their OpenID integration heavily on the "example app" provided by the project are at highest risk.

It was found that various OpenID Providers (OPs) had TLS Server Certificates that used weak keys, as a result of the Debian Predictable Random Number Generator (CVE-2008-0166). In combination with the DNS Cache Poisoning issue (CVE-2008-1447) and the fact that almost all SSL/TLS implementations do not consult CRLs (currently an untracked issue), this means that it is impossible to rely on these OPs.

message/ax/AxMessage.java in OpenID4Java before 0.9.6 final, as used in JBoss Enterprise Application Platform 5.1 before 5.1.2, Step2, Kay Framework before 1.0.2, and possibly other products does not verify that Attribute Exchange (AX) information is signed, which allows remote attackers to modify potentially sensitive AX information without detection via a man-in-the-middle (MITM) attack.