Threats / Microsoft / CVE-2020-0646
CVE-2020-0646
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft .NET Framework vulnerability
Microsoft .NET Framework contains an improper input validation vulnerability enabling remote code execution. The flaw has been exploited in the wild.
Verdict
Today item — known-exploited.
A remote code execution vulnerability in .NET Framework due to improper input validation. Active exploitation in the wild with high EPSS score indicates significant risk to deployed systems.
CISA KEV Yes · 2021-11-034EPSS 0.99222 (verify live)5CVSS 9.8 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: total3Exploit Weaponized · public exploit · Metasploit module8
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 2021-11-03).
Probability (EPSS)
EPSS 0.99222 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) · Affected: Microsoft, .NET Framework. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-91 XML Injection — weakness family: Injection.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · 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 659 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.
Public exploit available
Public exploit tooling is catalogued for this CVE (a functional/weaponized public exploit). Catalog entries: Metasploit module. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
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 malicious input that bypasses validation checks in .NET Framework processing logic.
Business
Attackers gain ability to execute arbitrary code on systems running vulnerable .NET Framework versions.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I deliver the malicious payload through network-accessible .NET applications without requiring authentication.
Business
Organizations face immediate compromise risk across web applications and services built on .NET Framework.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistent access and lateral movement within the compromised environment.
Business
Enterprise infrastructure integrity is compromised, enabling data theft, system manipulation, and operational disruption.
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