CVE-2026-22858

FreeRDP has a global-buffer-overflow in crypto_base64_decode

Published Jan 14, 2026 CVSS 4.0 · 5.6 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8105-1 FreeRDP vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*
Metrics 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'}

cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'}

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

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

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

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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 19, 2026, 12:05 PM
Reserved
Jan 12, 2026, 4:20 PM
Status
Modified
Published
Jan 14, 2026, 6:16 PM
Modified
Jul 15, 2026, 2:18 AM
Severity
Moderate
Public date
Jan 14, 2026, 5:56 PM