Threats / Microsoft / CVE-2021-27059
CVE-2021-27059
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Office vulnerability
Microsoft Office contains an unspecified remote code execution vulnerability that has been exploited in the wild.
Verdict
Today item — known-exploited.
This vulnerability enables unauthenticated remote code execution through Microsoft Office, likely via malicious document delivery. Active exploitation in the wild indicates immediate risk to organizations using affected Office versions.
CISA KEV Yes · 2021-11-035EPSS 0.03182 (verify live)6CVSS 7.63CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
3 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03).
Probability (EPSS)
EPSS 0.03182 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.6 (CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C) · Affected: Microsoft, Office. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 237 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
Craft a malicious Office document and distribute it via email or web to target users.
Business
Users open documents containing embedded exploit code, leading to unauthorized code execution on endpoints.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
Execute arbitrary commands with the privileges of the Office application process.
Business
Attackers gain initial access to corporate networks and can move laterally to sensitive systems.
3
Lateral reach — past segmentation narrative 3
Attacker
Establish persistence and exfiltrate data or deploy secondary payloads.
Business
Data breaches, intellectual property theft, and operational disruption across affected organizations.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05