Hazard

Is CVE-2021-33766 being exploited?

Weaponised and widely attempted

Reliable public exploit code exists, or mass exploitation attempts are probable. Patch inside days, not weeks.

Microsoft Exchange Server Information Disclosure

Microsoft · Exchange Server

CVSS 7.3 EPSS 98% no public exploit indexed Fix deadline passed 1 February 2022

What it is

Microsoft Exchange Server contains an information disclosure vulnerability which can allow an unauthenticated attacker to steal email traffic from target.

Why we say that

  • EPSS puts exploitation in the next 30 days at 98%
  • CISA's federal remediation deadline (2022-02-01) has passed
  • Listed in the CISA Known Exploited Vulnerabilities catalogue

Every line above comes from a named public source. Where the evidence is thin, we say so rather than inventing confidence — see methodology.

What to do

Apply updates per vendor instructions.

What it costs when this goes wrong

This is where UK enforcement meets the vulnerability record. Where an unfixed vulnerability leads to a breach, the ICO treats it as a security failure under UK GDPR. Recent cases:

All UK cases caused by unpatched software →