The embedded static NSS library, which is required to build the SunEC security provider, was affected by a vulnerability in the way NSS generated DSA signatures. A man-in-the-middle attacker could use this flaw during DSA signature generation to recover the private key. Erring on the side of caution, OpenJDK 7 was rebuilt against the latest version of NSS in Wheezy which provides a solution for this problem.
For Debian 7 Wheezy, these problems have been fixed in version 7u261-2.6.22-1~deb7u2.
We recommend that you upgrade your openjdk-7 packages.
Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/