CVE-2023-40187Public exploitNetwork attack vector

Client memory corruption via stale H.264 buffers

Published Aug 31, 2023 · Updated Feb 13, 2025

Use-after-free in FreeRDP clients 3.0.0-beta1 through 3.0.0-beta2 allows remote attackers to corrupt client memory via H.264 data. In avc420_ensure_buffer and avc444_ensure_buffer, a zero destination size frees YUV buffers but leaves their pointers unchanged. A crafted graphics update received by a FreeRDP-based client reaches the stale pointer and causes memory corruption or other unexpected behavior; the proxy is not affected.

CVSS severity7.3
High
EPSS probability1.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in FreeRDP clients 3.0.0-beta1 through 3.0.0-beta2 allows remote attackers to corrupt client memory via H.264 data. In avc420_ensure_buffer and avc444_ensure_buffer, a zero destination size frees YUV buffers but leaves their pointers unchanged. A crafted graphics update received by a FreeRDP-based client reaches the stale pointer and causes memory corruption or other unexpected behavior; the proxy is not affected.

The record

CVE
CVE-2023-40187
Published
Aug 31, 2023
Updated
Feb 13, 2025
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-416, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 31, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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=>= 3.0.0-beta1, < 3.0.0-beta3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=>= 3.0.0-beta1, < 3.0.0-beta3

Published CVSS scores

7.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

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 exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

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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