Opera Software has just released Opera 10.51 for Windows, which is a recommended security and stability update. As suggested by its version number, the changes are mostly under the hood and there are no new features.

This build addresses a couple of highly critical security issues, including the malformed HTTP Content-Length header issue, which we had discussed earlier;. The other security issue is related to XSLT (XSL Transformations). Due to a bug, it was possible to use certain XSLT constructs to retrieve random contents of unrelated documents (including sensitive data from previously visited websites).

Opera 10.51 also includes Carakan (Opera’s JavaScript engine) optimizations. As a result, it should be faster than ever before. In fact, PeaceKeeper scores can be 20-30% higher than in Opera 10.50. This is quite a significant achievement, since Carakan was already faster than its competitors.

The official changelog is fairly big and a large number of UI inconsistencies and bugs have been quashed in this release. Opera 10.51 can be downloaded from opera.com/download.