Based on our experience, however, we believe that more urgent action – within 7 days – is appropriate for critical vulnerabilities under active exploitation. The reason for this special designation is that each day an actively exploited vulnerability remains undisclosed to the public and unpatched, more computers will be compromised.
The presence of 0-day vulnerability exploitation is often a real and considerable threat to the Internet – particularly when very popular consumer-level software is the target. I think the stance of Chris Evans and Drew Hintz over at Google on a 60-day turnaround of vulnerability fixes from discovery, and a 7-day turnaround of fixes for actively exploited unpatched vulnerabilities, is rather naive and devoid of commercial reality.
As part of responsible disclosure I have always thought disclosing actively exploited vulnerabilities immediately is warranted. There are exceptions but users need to know they are at risk.
The downside is that if the attack is limited in nature, revealing vulnerability details exposes a wider user base.
Its a no-win situation, but I almost always err toward giving people the ability to defend themselves. Keep in mind that this is only for active, critical exploitation – not unexploited new vulnerabilities. Disclosing those without time to fix only hurts users.