USN-353-1 fixed several vulnerabilities in OpenSSL. However, Mark J Cox noticed that the applied patch for CVE-2006-2940 was flawed. This update corrects that patch.
For reference, this is the relevant part of the original advisory:
Certain types of public key could take disproportionate amounts of time to process. The library now limits the maximum key exponent size to avoid Denial of Service attacks. (CVE-2006-2940)