Threats / Microsoft / CVE-2009-0557
CVE-2009-0557
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Office vulnerability
Microsoft Office contains an object record corruption vulnerability in Excel that allows remote attackers to execute arbitrary code through crafted files.
Verdict
Today item — known-exploited.
A remote code execution vulnerability in Microsoft Office Excel triggered by malformed record objects in specially crafted spreadsheets. The vulnerability has been exploited in the wild and carries a high EPSS score of 0.86365, indicating significant practical exploitation risk.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
1 independent public report 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 2022-06-08).
Probability (EPSS)
EPSS 0.58551 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Microsoft, Office. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-94 Code Injection — weakness family: Injection.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
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
I craft a malicious Excel file with a corrupted object record and send it to a target user.
Business
An employee receives and opens the file, triggering remote code execution on corporate systems.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the code execution to establish persistence and move laterally within the network.
Business
Attackers gain unauthorized access to sensitive data, intellectual property, and critical business systems.
3
Lateral reach — past segmentation narrative 3
Attacker
I exfiltrate confidential information or deploy additional malware across the compromised infrastructure.
Business
The organization faces data breaches, operational disruption, regulatory penalties, and reputational damage.
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