CVE-2026-121955
Description
A flaw was found in FreeRDP. A use-after-free vulnerability exists in the smartcard emulation feature where a smartcard context is released before its background worker thread is properly terminated. A malicious server can exploit this by sending a crafted sequence of smartcard I/O Request Packets (IRPs) to a client with smartcard redirection enabled. Successful exploitation can corrupt memory or cause the client application to crash, leading to a Denial of Service (DoS).
Statement
This vulnerability is rated as an Important severity because an untrusted RDP server can remotely cause application crashes or heap corruption without requiring elevated privileges. The flaw affects client sessions where smartcard device redirection and emulation are actively configured, which is not engaged during standard RDP connections. In typical environments where smartcard forwarding is unused, client systems remain unaffected by this issue.
Mitigation
Do not enable smartcard redirection when establishing FreeRDP sessions.
Ensure client connection profiles and command-line invocations omit the `/smartcard` parameter (for example, launch connections using `xfreerdp /v:<server_address>` without the `/smartcard` switch). In graphical connection managers or RDP configuration files, disable smartcard forwarding. Additionally, only establish RDP sessions to trusted endpoints.
Caveats: Omitting smartcard redirection prevents the use of smartcard hardware tokens and smartcard-based authentication within the remote session.
--- CME Mitigation Guidance (2026-11-06) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to cancel and join the background worker thread prior to freeing the emulated SCardContext in FreeRDP smartcard emulation: upgrade to FreeRDP 3.32.2+ (or the fixed Freerdp builds), which cancel and join the background worker thread before freeing the emulated SCardContext in Emulate_SCardReleaseContext, closing crafted sequence of smartcard IRPs containing ESTABLISHCONTEXT, long-timeout GETSTATUSCHANGE, and RELEASECONTEXT. Until patched, this is a concern on FreeRDP client sessions with smartcard redirection and smartcard emulation enabled, so Omit the /smartcard parameter from connection profiles and command-line invocations, disable smartcard forwarding in connection managers, and only establish RDP sessions to trusted endpoints. These controls limit blast radius and contain exploitation, but they do not fix the underlying use-after-free defect — apply the upstream patch to fully remediate.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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