masci Banks up to 2.4.x Chat Message Parsing Prompt.chat_messages input validation

Summaryinfo

A vulnerability, which was classified as critical, has been found in masci Banks up to 2.4.x. This impacts the function Prompt.chat_messages of the component Chat Message Parsing. This manipulation causes input validation. This vulnerability appears as CVE-2026-107717. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in masci Banks up to 2.4.x and classified as critical. Affected by this vulnerability is the function Prompt.chat_messages of the component Chat Message Parsing. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Banks generates meaningful LLM prompts using a simple template language. Prior to 2.5.0, Banks Prompt.chat_messages() attempts to parse every line of rendered template output as ChatMessage JSON. When an application renders untrusted data and passes the returned ChatMessage objects to an LLM provider, attacker-controlled JSON can cross the prompt boundary and become a system, assistant, or tool message because ChatMessage.role accepts arbitrary strings. This can override application instructions, alter the intended prompt structure, or confuse downstream tool and message handling. This issue is fixed in version 2.5.0.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-107717 since 10/08/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available.

Upgrading to version 2.5.0 eliminates this vulnerability.

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Productinfo

Type

• Banking Software

Vendor

• masci

Name

• Banks

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4

Website

• Product: https://github.com/masci/banks/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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