CVE-2021-37595Network attack vector

Out-of-bounds access via unchecked clipboard file index

Published Jul 27, 2021 · Updated Aug 4, 2024

Improper input validation in FreeRDP before 2.4.0 on Windows allows remote attackers to trigger out-of-bounds access via a crafted PDU. wf_cliprdr_server_file_contents_request uses the request-controlled listIndex to index fileDescriptor or file_names without first comparing it with nFiles. A malicious RDP server must send the request to a connected wfreerdp client; published sources establish invalid memory access but no more specific reliable consequence.

CVSS severity9.8
Critical
EPSS probability1.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in FreeRDP before 2.4.0 on Windows allows remote attackers to trigger out-of-bounds access via a crafted PDU. wf_cliprdr_server_file_contents_request uses the request-controlled listIndex to index fileDescriptor or file_names without first comparing it with nFiles. A malicious RDP server must send the request to a connected wfreerdp client; published sources establish invalid memory access but no more specific reliable consequence.

The record

CVE
CVE-2021-37595
Published
Jul 27, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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