CVE-2026-22858 — FreeRDP has a global-buffer-overflow in crypto_base64_decode

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
FreeRDP / FreeRDP	affected < 3.20.1

CWE

CWE-125, CWE-758

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A global buffer overflow flaw has been discovered in FreeRDP. This 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.