Third-party plug-ins can be a real pain in the back for browser developers. Security holes constantly show up in Adobe Flash and Reader, for example, leaving those running out-of-date versions open to potential remote execution exploits or enduring stability issues.

Looking to minimize the threat, Mozilla has revealed it will start prompting users to update old plug-ins whenever users visit a website that requires them.

Old versions of Silverlight, Adobe Reader and Adobe Flash on Windows will trigger a warning message. The company didn't say when the warnings system will go live, what they will look like, or which versions of Firefox will support this.

Users are free to ignore the warnings and continue using their old plugins, though Mozilla advises users to visit the Plugin Check page and update them as soon as possible.

Users of other browsers can also visit Mozilla's Plugin Check page directly to update their plugins and stay clear of potential vulnerabilities. Launched in 2009, the site tracks over 15 popular plugins, and works with Windows, Mac or Linux variants of Chrome, Opera, Firefox, Safari and Internet Explorer.

Google handles the issue a bit differently with Flash built-in in their Chrome browser and updated with each release. PDF support is also native but other third-party plugins are not automatically covered.