'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.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-375f-4r2h-f99j | Bandit trusts client-supplied URI scheme on plaintext connections |
Sat, 02 May 2026 02:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Fri, 01 May 2026 21:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | Client-supplied URI scheme trusted without transport verification in bandit | |
| First Time appeared |
Mtrudel
Mtrudel bandit |
|
| Weaknesses | CWE-807 | |
| CPEs | cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Mtrudel
Mtrudel bandit |
|
| References |
| |
| Metrics |
cvssV4_0
|
Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-05-04T17:11:38.567Z
Reserved: 2026-04-07T12:28:54.916Z
Link: CVE-2026-39807
Updated: 2026-05-02T01:18:06.333Z
Status : Deferred
Published: 2026-05-01T21:16:17.180
Modified: 2026-05-05T19:37:28.367
Link: CVE-2026-39807
No data.
OpenCVE Enrichment
Updated: 2026-05-02T00:30:15Z
Github GHSA