CVE-2026-39807
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.
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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
- Versión: 4.0
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Puntuación base: 6.3
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.52%
- Percentil entre todas las CVEs puntuadas: 43
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-807
Referencias
- https://cna.erlef.org/cves/CVE-2026-39807.html
- https://github.com/mtrudel/bandit/commit/45feea20dea8af7ffd7245271107b695c040e667
- https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j
- https://osv.dev/vulnerability/EEF-CVE-2026-39807
- https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j
JSON original (NVD)
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{
"id": "CVE-2026-39807",
"cveTags": [],
"metrics": {
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"id": "CVE-2026-39807",
"role": "CISA Coordinator",
"options": [
{
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},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
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],
"version": "2.0.3",
"timestamp": "2026-05-02T01:17:52.498343Z"
}
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"attackVector": "NETWORK",
"baseSeverity": "MEDIUM",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"exploitMaturity": "NOT_DEFINED",
"providerUrgency": "NOT_DEFINED",
"userInteraction": "NONE",
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"attackRequirements": "PRESENT",
"privilegesRequired": "NONE",
"subIntegrityImpact": "NONE",
"vulnIntegrityImpact": "LOW",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"vulnAvailabilityImpact": "NONE",
"availabilityRequirement": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"subConfidentialityImpact": "NONE",
"vulnConfidentialityImpact": "LOW",
"confidentialityRequirement": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
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"vulnerabilityResponseEffort": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED"
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"affected": [
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"affectedData": [
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"vendor": "mtrudel",
"modules": [
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"packageURL": "pkg:hex/bandit",
"packageName": "bandit",
"programFiles": [
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"collectionURL": "https://repo.hex.pm",
"defaultStatus": "unaffected",
"programRoutines": [
{
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"published": "2026-05-01T21:16:17.180",
"references": [
{
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"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
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{
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"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
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{
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"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
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{
"url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
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],
"vulnStatus": "Deferred",
"weaknesses": [
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"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"description": [
{
"lang": "en",
"value": "CWE-807"
}
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"descriptions": [
{
"lang": "en",
"value": "Reliance on Untrusted Inputs in a Security Decision vulnerability in mtrudel bandit allows unauthenticated transport-state spoofing on plaintext HTTP connections.\n\n'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.\n\nDownstream 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.\n\nThis issue affects bandit: from 1.0.0 before 1.11.0."
}
],
"lastModified": "2026-06-17T10:42:36.757",
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}