CVE-2017-20201

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.49% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 40.1% of scored records. A rank, not a probability.

NVD base score

9.3 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Deferred. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2025-10-08 22:04Z11 MO AGO

Last updated

2025-11-21 14:11Z9 MO AGO

Reserved

2025-10-08

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

Critical (CVSS 9.3)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N

Weaknesses

• CWE-506Embedded Malicious CodeClass

Data version

5.2

Document digest

bb3f38b68f89385a20c360ac2d14737cfe4380e87297f2abf585fa709f233f58

• blog.avast.comhttps://blog.avast.com/update-to-the-ccleaner-5.33.6162-security-incidentvendor-advisory
• blog.avast.comhttps://blog.avast.com/progress-on-ccleaner-investigationvendor-advisory
• www.ccleaner.comhttps://www.ccleaner.com/product
• www.crowdstrike.comhttps://www.crowdstrike.com/en-us/blog/protecting-software-supply-chain-deep-insights-ccleaner-backdoor/technical-description
• www.ccleaner.comhttps://www.ccleaner.com/knowledge/security-notification-ccleaner-v5336162-ccleaner-cloud-v1073191vendor-advisorypatch
• www.morphisec.comhttps://www.morphisec.com/blog/morphisec-discovers-ccleaner-backdoor/technical-description
• blog.talosintelligence.comhttps://blog.talosintelligence.com/avast-distributes-malware/technical-description
• www.vulncheck.comhttps://www.vulncheck.com/advisories/ccleaner-and-ccleaner-cloud-malicious-backdoor-supply-chain-compromisethird-party-advisory