CVE-2026-55827

Memory Safety in Freerdp ≤ 3.27.1

Public PoCMemory Safety

Published

10 July 2026

Modified

15 July 2026

Patch / advisory

View advisory

CVSS Score v3.1 7.5

Click a component to see what it means

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Score 0.0034 27th percentile

Risk Priority 56 floored blend · peak EPSS

Summary

CVE-2026-55827 is a high-severity Incorrect Calculation of Buffer Size (CWE-131) vulnerability in Freerdp Freerdp. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 27th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-43004

Vulnerability Data

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.1, FreeRDP clients launched with the non-default /cache:codec:rfx option pass desktop stride and height to RemoteFX decoding for Cache Bitmap V3 data while allocating bitmap->data only for the…

smaller DstWidth and DstHeight in gdi_Bitmap_Decompress, allowing a malicious RDP server to trigger a heap out-of-bounds write with attacker-controlled offset and content. This issue is fixed in version 3.27.1.

CWE(s): CWE-131 CWE-787

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1211 Exploitation for Stealth Stealth

Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.

attack.mitre.org →

T1212 Exploitation for Credential Access Credential Access

Adversaries may exploit software vulnerabilities in an attempt to collect credentials.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-40574Same product: Freerdp Freerdp

CVE-2026-33985Same product: Freerdp Freerdp

CVE-2026-44420Same product: Freerdp Freerdp

CVE-2026-33986Same product: Freerdp Freerdp

CVE-2026-31806Same product: Freerdp Freerdp

CVE-2026-33984Same product: Freerdp Freerdp

CVE-2026-33987Same product: Freerdp Freerdp

CVE-2024-32039Same product: Freerdp Freerdp

CVE-2023-40569Same product: Freerdp Freerdp

CVE-2023-39352Same product: Freerdp Freerdp

Affected Assets

freerdp

≤ 3.27.1

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer security testing and code review can discover incorrect buffer-size computations before deployment.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented secure-development standards and tools can mandate bounds-checked coding practices that avoid the weakness.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles directly require correct buffer-size arithmetic and bounds-checked allocation.

SI-10 Information Input Validation partial match

Input validation can enforce that supplied lengths or counts used in size calculations are within safe bounds.

SI-16 Memory Protection partial match

Memory-protection mechanisms limit the exploitability of an overflow that results from an incorrect size calculation.

SI-2 Flaw Remediation partial match

Flaw-remediation processes that include vulnerability scanning or static analysis will surface buffer-size errors.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match

prevents

Secure SDLC practices directly prevent buffer-size miscalculations via coding standards, reviews, and testing, while fixing this single weakness only partially fulfills the broader control.

ID.RA-01 partial match

prevents

Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.

PR.PS-02 partial match

prevents

Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match

degrades

Secure coding standards directly require correct buffer-size calculations.

A.8.29 Security testing in development and acceptance mostly match

finds

Security testing can detect buffer-size errors before release.

A.8.25 Secure development life cycle partial match

prevents

Secure development lifecycle mandates size-checking practices that reduce buffer-size miscalculations.

A.8.26 Application security requirements partial match

prevents

Application security requirements can specify buffer-size validation rules.