Matt Linton, a senior security engineer at Google, and colleague Pat Parseghian, technical program manager, said the company had decided to go public about the problem prior to a planned "coordinated disclosure date" of 9 January following reports of the issue in the media.
The Register reported on the existence of the 'Meltdown' and 'Spectre' flaws on Wednesday.
In a blog, Linton and Parseghian said that the "serious security flaws" had been identified by security researchers in Google's 'Project Zero' team last year. The vulnerabilities arise from a method "most modern processors" deploy to "optimise performance", they said.
"The Project Zero researchers discovered three methods (variants) of attack, which are effective under different conditions," according to the blog. "All three attack variants can allow a process with normal user privileges to perform unauthorised reads of memory data, which may contain sensitive information such as passwords, cryptographic key material, etc."
"In order to improve performance, many CPUs may choose to speculatively execute instructions based on assumptions that are considered likely to be true. During speculative execution, the processor is verifying these assumptions; if they are valid, then the execution continues. If they are invalid, then the execution is unwound, and the correct execution path can be started based on the actual conditions. It is possible for this speculative execution to have side effects which are not restored when the CPU state is unwound, and can lead to information disclosure," it said.
"There is no single fix for all three attack variants; each requires protection independently. Many vendors have patches available for one or more of these attacks," it said.
Processor giant Intel, one of the companies whose products are potentially exposed by the flaws, said it is "working closely with many other technology companies, including AMD, ARM Holdings and several operating system vendors, to develop an industry-wide approach to resolve this issue promptly and constructively".
In a statement, Intel said it has "begun providing software and firmware updates to mitigate these exploits".
“Check with your operating system vendor or system manufacturer and apply any available updates as soon as they are available," Intel said. "Following good security practices that protect against malware in general will also help protect against possible exploitation until updates can be applied."
“Intel believes its products are the most secure in the world and that, with the support of its partners, the current solutions to this issue provide the best possible security for its customers," it said.