Threats / Microsoft / CVE-2020-1020
CVE-2020-1020
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft Windows vulnerability
Microsoft Windows Adobe Font Manager Library remote code execution vulnerability via specially crafted multi-master fonts. Allows RCE on non-Windows 10 systems; limited AppContainer execution on Windows 10.
Verdict
Today item — known-exploited.
An attacker can achieve remote code execution by crafting malicious multi-master Adobe Type 1 PostScript fonts. On Windows 10, exploitation results in sandboxed execution; on earlier versions, full system compromise is possible.
CISA KEV Yes · 2021-11-034EPSS 0.65037 (verify live)5Exploit Public PoC6CVSS 8.8 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported 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 0.65037 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) · Affected: Microsoft, Windows. 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-787 Out-of-bounds Write — weakness family: Memory safety.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: 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 567 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
I craft a malicious multi-master Adobe Type 1 PostScript font file and distribute it via email, web, or document embedding.
Business
End users receive compromised font files through routine communication channels, increasing infection surface.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I trigger font parsing when the victim opens a document or application that loads the malicious font through the Adobe Font Manager Library.
Business
Standard user workflows like opening documents or viewing web content become attack vectors without additional user interaction.
3
Lateral reach — past segmentation narrative 3
Attacker
I exploit the buffer overflow in font handling to execute arbitrary code with the privileges of the application processing the font.
Business
On pre-Windows 10 systems, attackers gain full system access; on Windows 10, code runs in restricted AppContainer context limiting lateral movement.
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