Hazard

Is CVE-2021-3156 being exploited?

Weaponised and widely attempted

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

Sudo Heap-Based Buffer Overflow Vulnerability

Sudo · Sudo

CVSS 7.8 EPSS 99% 2 public exploits Fix deadline passed 27 April 2022

What it is

Sudo contains an off-by-one error that can result in a heap-based buffer overflow, which allows for privilege escalation.

Why we say that

  • EPSS puts exploitation in the next 30 days at 99%
  • 2 public exploits published
  • CISA's federal remediation deadline (2022-04-27) 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.

Public exploit code

Indexed from Exploit-DB. Presence of code raises urgency; absence does not mean safety.

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 →