Cyber Posture

CVE-2026-40033

HighPublic PoC
Microsoft: not affectedMSmacOS: not affectedMacLinux: not affectedLnxMobile: not affectedMobNetwork: not affectedNetApplication: affectedAppOther: not affectedOth

Published: 26 May 2026

Published
26 May 2026
Modified
27 May 2026
KEV Added
—
Patch
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CVSS Score 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.0005 15.9th percentile
Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-40033 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Freerdp Freerdp. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 15.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploitation for Client Execution (T1203).
Threat & Defense Details

MITRE ATT&CK Enterprise TechniquesAI

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
Why these techniques?

Heap buffer overflow in RDP client (FreeRDP) enables remote code execution via malicious server, directly mapping to client-side exploitation technique.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions, enabling malicious RDP…

more

servers to trigger large out-of-bounds writes and potentially achieve remote code execution or client crash.

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)
CWE-122

Affected Products

freerdp
freerdp
≤ 3.26.0

EU & UK References

References