Opera Software has patched seven vulnerabilities in its flagship Opera browser, but declined to provide information about one of the bugs.
The Norwegian browser developer hinted that other programs, not yet unpatched, were also affected by the flaw.
Wednesday's update to Opera 9.52 fixes multiple bugs - seven in the Windows version, five in the Mac edition and six in the Linux browser - that range from "extremely severe" to "not severe" in the company's five-step threat ranking system.
What was unusual, however, was that Opera omitted an explanation for one of the fixed flaws. Instead, the company simply stated in the change log: "Fixed an issue that could allow cross-site scripting, as reported by Chris Weber of Casaba Security: details will be disclosed at a later date."
When asked for more information on the cross-site scripting vulnerability, Opera spokesman Thomas Ford hinted that other software might be involved. "Opera thinks it is acceptable under specific circumstances to release a security update without publishing an advisory for the specific bug," said Ford in an email response to questions. "If we publish without an advisory, it is often because other vendors have not issued patches."
Other vendors have occasionally refused to provide details on what they've patched, even though they customarily publish that information simultaneously with a fix. Last February, for example, when Adobe Systems updated its popular Reader PDF utility to quash "a number of ... security vulnerabilities," it did not provide any information on the bugs it found and fixed. At the time, the behavior puzzled security researchers, who noted that Adobe was usually more forthcoming.
Adobe waited three months to publish advisories that outlined eight different vulnerabilities, prompting some experts to speculate that the company believed the severity of the bugs justified the secrecy.
Opera's Ford, however, said that his company's secrecy had different motives. "Publishing a full advisory only because we've patched something could leave users of other products unprotected while giving malicious hackers the information needed to cause damage," he said.
The cross-site scripting vulnerability was patched for the Windows, Mac and Linux versions of Opera.
Chris Weber, the researcher with Casaba Security who was credited by Opera with reporting the bug, did not respond to a call for comment.
Opera also fixed a protocol handler flaw rated "extremely severe" in Windows, spoofing bugs, and a vulnerability in the browser's custom shortcuts feature that could let attackers inject malicious code into the Windows, Linux, FreeBSD and Solaris versions.
The 9.52 update also addressed numerous non-security bugs in the user interface, the Opera email and chat clients, and other components. It also included stability and reliability improvements that fixed problems using the browser to reach Google's Gmail online email service and a memory leak in Opera's BitTorrent code.
Opera 9.52 can be downloaded from the Opera site.