CVE-2023-40589Public exploitNetwork attack vector

Client crash via unchecked NCRUSH lookup indexes

Published Aug 31, 2023 · Updated Nov 3, 2025

Buffer overflow in FreeRDP before 2.11.0 and 3.0.0-beta1 through 3.0.0-beta2 allows remote attackers to crash RDP clients. The ncrush_decompress decoder uses values derived from crafted compressed RDP data as LOMBitsLUT and LOMBaseLUT indexes without first verifying their bounds. A client must connect to a malicious or compromised RDP server that sends the crafted compressed data; the demonstrated consequence is a client crash only.

CVSS severity7.5
High
EPSS probability1.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in FreeRDP before 2.11.0 and 3.0.0-beta1 through 3.0.0-beta2 allows remote attackers to crash RDP clients. The ncrush_decompress decoder uses values derived from crafted compressed RDP data as LOMBitsLUT and LOMBaseLUT indexes without first verifying their bounds. A client must connect to a malicious or compromised RDP server that sends the crafted compressed data; the demonstrated consequence is a client crash only.

The record

CVE
CVE-2023-40589
Published
Aug 31, 2023
Updated
Nov 3, 2025
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-120, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 31, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record 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=< 2.11.0
  2. Affected versionversion=>= 3.0.0-beta1, < 3.0.0-beta3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=< 2.11.0; version=>= 3.0.0-beta1, < 3.0.0-beta3

Published CVSS scores

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

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

Public exploit references

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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