Reliance on Untrusted Inputs in a Security Decision vulnerability in mtrudel bandit allows unauthenticated transport-state spoofing on plaintext HTTP connections.
'Elixir.Bandit.Pipeline':determine_scheme/2 in lib/bandit/pipeline.ex returns the client-supplied URI scheme verbatim, ignoring the transport's secure? flag. HTTP/1.1 absolute-form request targets (e.g. GET https://victim/path HTTP/1.1) and the HTTP/2 :scheme pseudo-header are both attacker-controlled strings that flow through this function. Over a plaintext TCP connection, a client can declare https and Bandit will set conn.scheme = :https even though no TLS was negotiated.
Downstream Plug consumers that branch on conn.scheme are silently misled: Plug.SSL's already-secure branch skips its HTTP→HTTPS redirect, cookies emitted with secure: true are sent over plaintext, audit logs record requests as having arrived over HTTPS, and CSRF/SameSite gating may make incorrect decisions.
This issue affects bandit: from 1.0.0 before 1.11.0.
CVSS
No CVSS.
References
Configurations
No configuration.
History
02 May 2026, 02:16
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j - |
01 May 2026, 21:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-01 21:16
Updated : 2026-05-05 19:37
NVD link : CVE-2026-39807
Mitre link : CVE-2026-39807
CVE.ORG link : CVE-2026-39807
JSON object : View
Products Affected
No product.
CWE
CWE-807
Reliance on Untrusted Inputs in a Security Decision