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CRITICAL · 9.1

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-def...

Vulnerability 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.

CVSS Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
HIGH

Affected Products

VendorProductVersions
FreerdpFreerdp< 3.20.1

Related Weaknesses (CWE)

CWE-758CWE-125

References

FAQ

What is CVE-2026-22858?

CVE-2026-22858 is a vulnerability with a CVSS score of 9.1 (CRITICAL). 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-def...

How severe is CVE-2026-22858?

CVE-2026-22858 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-22858?

Check the references section above for vendor advisories and patch information. Affected products include: Freerdp Freerdp.