Researchers discovered two flaws in OpenSSL, a Secure Socket Layer (SSL) library and related cryptographic tools. Applications that are linked against this library are generally vulnerable to attacks that could leak the server's private key or make the encrypted session decryptable otherwise. The Common Vulnerabilities and Exposures (CVE) project identified the following vulnerabilities:
For the stable distribution (woody) these problems have been fixed in version 0.9.6c-2.woody.3.
For the old stable distribution (potato) these problems have been fixed in version 0.9.6c-0.potato.6.
For the unstable distribution (sid) these problems have been fixed in version 0.9.7b-1 of openssl and version 0.9.6j-1 of openssl096.
We recommend that you upgrade your openssl packages immediately and restart the applications that use OpenSSL.
Unfortunately, RSA blinding is not thread-safe and will cause failures for programs that use threads and OpenSSL such as stunnel. However, since the proposed fix would change the binary interface (ABI), programs that are dynamically linked against OpenSSL won't run anymore. This is a dilemma we can't solve.
You will have to decide whether you want the security update which is not thread-safe and recompile all applications that apparently fail after the upgrade, or fetch the additional source packages at the end of this advisory, recompile it and use a thread-safe OpenSSL library again, but also recompile all applications that make use of it (such as apache-ssl, mod_ssl, ssh etc.).
However, since only very few packages use threads and link against the OpenSSL library most users will be able to use packages from this update without any problems.
MD5 checksums of the listed files are available in the original advisory.