CVE-2026-27015: FreeRDP: Smartcard NDR Alignment Padding Triggers Reachable WINPR_ASSERT Abort (Client DoS)

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-25 · updated 2026-06-17
Weakness: CWE-617

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, a missing bounds check in `smartcard_unpack_read_size_align()` (`libfreerdp/utils/smartcard_pack.c:1703`) allows a malicious RDP server to crash the FreeRDP client via a reachable `WINPR_ASSERT` → `abort()`. The crash occurs in upstream builds where `WITH_VERBOSE_WINPR_ASSERT=ON` (default in FreeRDP 3.22.0 / current WinPR CMake defaults). Smartcard redirection must be explicitly enabled by the user (e.g., `xfreerdp /smartcard`; `/smartcard-logon` implies `/smartcard`). Version 3.23.0 fixes the issue.

Affected products

FreeRDP: before 3.23.0 — fixed in 3.23.0

How to fix

Upgrade to a fixed version: FreeRDP 3.23.0. Check the vendor advisory for mitigations.

References

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