Cyber Resilience

CVE-2026-22859

Memory Safety in Freerdp ≤ 3.20.1

Public PoCMemory Safety
Published
14 January 2026
Modified
15 July 2026
Patch / advisory
View advisory
CVSS Score v4 5.6
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0076 52th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-22859 is a medium-severity Out-of-bounds Read (CWE-125) vulnerability in Freerdp Freerdp. Its CVSS base score is 5.6 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 48% of CVEs by exploit likelihood; 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-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-22859 is a high-severity vulnerability in FreeRDP, an open-source implementation of the Remote Desktop Protocol (RDP). Prior to version 3.20.1, the URBDRC client component fails to perform bounds checking on server-supplied MSUSB_INTERFACE_DESCRIPTOR values, which are then used as indices in the libusb_udev_complete_msconfig_setup function. This flaw results in an out-of-bounds read, corresponding to CWE-125 (Out-of-bounds Read) and CWE-129 (Improper Validation of Array Index). The issue carries a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H).

A remote attacker can exploit this vulnerability by operating a malicious RDP server. When a victim uses a vulnerable FreeRDP client (versions before 3.20.1) to connect to the attacker's server, the attacker can supply crafted MSUSB_INTERFACE_DESCRIPTOR values during the session. This triggers the out-of-bounds read on the client side, potentially allowing the attacker to disclose sensitive information from memory (high confidentiality impact) or cause a denial of service via client crash (high availability impact). Exploitation requires no privileges, user interaction, or special conditions, making it accessible over the network with low complexity.

The FreeRDP project addresses this vulnerability in version 3.20.1, as detailed in the release notes and security advisory. Security practitioners should advise users to update FreeRDP clients to 3.20.1 or later to mitigate the issue. Relevant resources include the GitHub release page at https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1 and the advisory at https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-56f5-76qv-2r36.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.20.1, the URBDRC client does not perform bounds checking on server‑supplied MSUSB_INTERFACE_DESCRIPTOR values and uses them as indices in libusb_udev_complete_msconfig_setup, causing an out‑of‑bounds read. This vulnerability is fixed…

more

in 3.20.1.

CWE(s)
CWE-125CWE-129

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-2023-40576Same product: Freerdp Freerdp
CVE-2023-40575Same product: Freerdp Freerdp
CVE-2026-57157Same product: Freerdp Freerdp
CVE-2026-22855Same product: Freerdp Freerdp
CVE-2025-68118Same product: Freerdp Freerdp
CVE-2026-57158Same product: Freerdp Freerdp
CVE-2026-31885Same product: Freerdp Freerdp
CVE-2026-25942Same product: Freerdp Freerdp
CVE-2026-31897Same product: Freerdp Freerdp
CVE-2026-33982Same product: Freerdp Freerdp

Affected Assets

freerdp
freerdp
≤ 3.20.1

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation directly finds out-of-bounds read flaws through static analysis, fuzzing, and dynamic bounds checks.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require bounds checking and memory-safe constructs that stop out-of-bounds reads from being introduced.

SC-39 Process Isolation partial match

Process isolation confines the effects of an out-of-bounds read to the compromised process.

SI-10 Information Input Validation partial match

Input validation rejects malformed indices or lengths that would otherwise cause reads outside buffer bounds.

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-development practices such as bounds checking and memory-safe languages directly prevent out-of-bounds reads.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover instances of out-of-bounds reads after code is deployed.

PR.PS-02 partial match
prevents

Routine patching replaces vulnerable code containing out-of-bounds read flaws.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance includes fuzzing and static analysis that detect out-of-bounds read defects before release.

A.8.15 Logging partial match
finds

Logging can record evidence of an out-of-bounds read but does not prevent the weakness itself.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and bounds checking that directly prevent out-of-bounds reads.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit bounds and memory-safety specifications that mitigate buffer over-reads.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles require memory-safe design patterns and runtime protections against out-of-bounds access.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe pointer arithmetic and mandate bounds-checked reads, eliminating CWE-125.

References