CVE-2026-44209 Banks: Critical Remote Code Execution (RCE) via Jinja2 SSTI
Attackers can execute arbitrary code on the host system by injecting malicious templates into the Banks library if user input is passed directly to the prompt renderer.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-44209?
CVE-2026-44209 is a high-severity code injection vulnerability in masci banks, published on 26 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Banks generates meaningful LLM prompts using a template language that makes sense. Prior to 2.4.2, banks uses jinja2.Environment() (unsandboxed) to render prompt templates. Applications that pass user-supplied strings as the template argument to Prompt() are vulnerable to Server-Side Template Injection (SSTI), which can lead to Remote Code Execution (RCE) on the host system. This vulnerability is fixed in 2.4.2.
Which versions are affected by CVE-2026-44209?
3 open source packages ship an affected version, including banks.
| Package | Affected | Fixed in |
|---|---|---|
banks PyPI | All versions | 2.4.2 |
banks PyPI | All versions | 2.4.2 |
banks PyPI | All versions | 2.4.2 |
How do I fix CVE-2026-44209?
Upgrade banks to 2.4.2 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-44209 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44209 exists.
Sources
Also known as GHSA-gphh-9q3h-jgpp, PYSEC-2026-2390.