CVE-2021-41159Network attack vector

Client memory corruption via unchecked RPC gateway input

Published Oct 21, 2021 · Updated Aug 4, 2024

Out-of-bounds write in FreeRDP clients before 2.4.1 allows remote attackers operating a malicious gateway to corrupt client memory. The legacy RPC gateway parser manually reads gateway-controlled packet fields without adequate bounds validation, allowing malformed input to drive writes beyond allocated client buffers. Exploitation requires a client to initiate a /gt:rpc connection to an attacker-controlled gateway; direct and /gt:http connections do not expose this parser.

CVSS severity8.8
High
EPSS probability1.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in FreeRDP clients before 2.4.1 allows remote attackers operating a malicious gateway to corrupt client memory. The legacy RPC gateway parser manually reads gateway-controlled packet fields without adequate bounds validation, allowing malformed input to drive writes beyond allocated client buffers. Exploitation requires a client to initiate a /gt:rpc connection to an attacker-controlled gateway; direct and /gt:http connections do not expose this parser.

The record

CVE
CVE-2021-41159
Published
Oct 21, 2021
Updated
Aug 4, 2024
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 21, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 2.4.1

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

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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