CVE-2026-23534
Description
A flaw was found in FreeRDP, a free implementation of the Remote Desktop Protocol. A malicious server can trigger a client-side heap buffer overflow in the ClearCodec bands decode path. This vulnerability, caused by crafted band coordinates, allows writes past the end of the destination surface buffer. Successful exploitation can lead to a crash, resulting in a denial of service (DoS), and potentially arbitrary code execution.
Statement
For this vulnerability to be exploited, a client must connect to a maliciously-configured server. Red Hat recommends that FreeRDP clients are only used to connect to trusted servers.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.6 | 9.8 | 7.6 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | Required | None | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | High | Low |
| Integrity Impact | Low | High | Low |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Modify Memory
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. Besides important user data, heap-based overflows can be used to overwrite function pointers that may be living in memory, pointing it to the attacker's code. Even in applications that do not explicitly use function pointers, the run-time will usually leave many in memory. For example, object methods in C++ are generally implemented using function pointers. Even in C programs, there is often a global offset table used by the underlying runtime.
Integrity,Confidentiality,Availability,Access Control,Other
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Other
When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
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