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.
Advisories

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Fixes

Solution

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Workaround

No workaround given by the vendor.

History

Thu, 15 Jan 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:L'}

threat_severity

Moderate


Thu, 15 Jan 2026 08:15:00 +0000

Type Values Removed Values Added
First Time appeared Freerdp
Freerdp freerdp
Vendors & Products Freerdp
Freerdp freerdp

Wed, 14 Jan 2026 22:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 14 Jan 2026 18:00:00 +0000

Type Values Removed Values Added
Description 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.
Title FreeRDP has a global-buffer-overflow in crypto_base64_decode
Weaknesses CWE-125
CWE-758
References
Metrics cvssV4_0

{'score': 5.6, 'vector': 'CVSS: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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-01-14T21:12:03.734Z

Reserved: 2026-01-12T16:20:16.746Z

Link: CVE-2026-22858

cve-icon Vulnrichment

Updated: 2026-01-14T21:12:00.311Z

cve-icon NVD

Status : Received

Published: 2026-01-14T18:16:43.520

Modified: 2026-01-14T18:16:43.520

Link: CVE-2026-22858

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-01-14T17:56:29Z

Links: CVE-2026-22858 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-01-15T08:03:21Z

Weaknesses