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.
Fix
Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.
Change history 1
- First seenCVSS 6.5NVD modified 2026-10-13 17:17
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 5
- https://github.com/masci/banks/commit/02172b816fb84f6a824cc09a8aca7416f53c12cb
- https://github.com/masci/banks/pull/78
- https://github.com/masci/banks/releases/tag/v2.5.0
- https://github.com/masci/banks/security/advisories/GHSA-hmq2-7hp6-7crh
- https://github.com/masci/banks/security/advisories/GHSA-hmq2-7hp6-7crh