August will be another substantial patch month for Microsoft, with the vendor releasing 12 security bulletins next Tuesday to fix holes in its Windows OS (operating system) and the Office productivity suite.

Ten of the patches will affect Windows, with at least one rated as a 'critical' update. The other two security updates, at least one of which is also rated critical, affect Office. Critical flaws are those than can be exploited by attackers to run unauthorised code on a PC without any user action.

The patches, some of which will require a restart, will be released on 8 August as part of Microsoft's regularly scheduled monthly security update, which security researchers call Patch Tuesday. Microsoft's advance note on the updates can be found here.

Also on Tuesday, Microsoft will release an updated version of its Windows Malicious Software Removal Tool on Windows Update, Microsoft Update, Windows Server Update Services and the Download Center. The company will also release two non-security high-priority updates for Windows on Windows Update and Software Update Services.

Patch Tuesday has been keeping system administrators busy lately as the company has responded to hacker attacks on unpatched flaws in its software – particularly a series of attacks on its Excel spreadsheet software.

Microsoft released seven patches in July, some of which addressed the much-publicised Excel bugs confirmed in June. System administrators were also busy with regularly scheduled monthly patches that month, as Microsoft released 12 security updates.