CVE-2026-22858

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.20.1, global-buffer-overflow was observed in FreeRDP's Base64 decoding path. The root cause appears to be implementation-defined char signedness: on Arm/AArch64 builds, plain char is treated as unsigned, so the guard c <= 0 can be optimized into a simple c != 0 check. As a result, non-ASCII bytes (e.g., 0x80-0xFF) may bypass the intended range restriction and be used as an index into a global lookup table, causing out-of-bounds access. This vulnerability is fixed in 3.20.1.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1	Release Notes
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmqf-m84q-x896	Vendor Advisory Exploit

Configurations

Configuration 1 (hide)

cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*

History

20 Jan 2026, 18:33

Type	Values Removed	Values Added
References	~~() https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1 -~~	() https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1 - Release Notes
References	~~() https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmqf-m84q-x896 -~~	() https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmqf-m84q-x896 - Vendor Advisory, Exploit
First Time		Freerdp Freerdp freerdp
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.1
CPE		cpe:2.3:a:freerdp:freerdp::::::::

14 Jan 2026, 18:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-01-14 18:16

Updated : 2026-01-20 18:33

NVD link : CVE-2026-22858

Mitre link : CVE-2026-22858

CVE.ORG link : CVE-2026-22858

JSON object : View

Products Affected

freerdp

freerdp

CWE

CWE-125

Out-of-bounds Read

CWE-758

Reliance on Undefined, Unspecified, or Implementation-Defined Behavior

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