FreeRDP up to 3.30.x Negotiation nego_send_negotiation_request heap-based overflow

Summaryinfo

A vulnerability categorized as critical has been discovered in FreeRDP up to 3.30.x. This vulnerability affects the function nego_send_negotiation_request of the component Negotiation. The manipulation results in heap-based overflow. This vulnerability is identified as CVE-2026-91964. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in FreeRDP up to 3.30.x. It has been classified as critical. Affected is the function nego_send_negotiation_request of the component Negotiation. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

FreeRDP versions before 3.31.0 contain a heap-based buffer overflow in nego_send_negotiation_request when processing Server Redirection PDU messages with attacker-controlled LoadBalanceInfo fields. A malicious RDP server can trigger the overflow by sending an arbitrary-length field that gets written to a fixed 512-byte buffer without validation, causing client crashes or potential code execution when chained with memory disclosure.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-91964 since 09/15/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 3.31.0 eliminates this vulnerability.

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Productinfo

Type

• Remote Access Software

Name

• FreeRDP

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14
• 3.15
• 3.16
• 3.17
• 3.18
• 3.19
• 3.20
• 3.21
• 3.22
• 3.23
• 3.24
• 3.25
• 3.26
• 3.27
• 3.28
• 3.29
• 3.30

License

• open-source

Website

• Product: https://github.com/FreeRDP/FreeRDP/

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