Reliance on Untrusted Inputs in a Security Decision Affecting bandit package, versions >=1.0.0 <1.11.0
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-HEX-BANDIT-16347191
- published3 May 2026
- disclosed1 May 2026
- creditPJUllrich
Introduced: 1 May 2026
NewCVE-2026-39807 (opens in a new tab)How to fix?
Upgrade bandit to version 1.11.0 or higher.
Overview
bandit is a HTTP server for Plug and WebSock apps.
Affected versions of this package are vulnerable to Reliance on Untrusted Inputs in a Security Decision via the determine_scheme logic in Bandit.Pipeline. An attacker can make the application report an attacker-chosen scheme value by sending an absolute-form HTTP/1.1 request target or HTTP/2 :scheme header that disagrees with the actual transport. This can cause downstream code to treat an insecure request as https or a secure request as http, breaking URL generation, redirects, and any application logic that relies on the connection scheme.