{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-39807", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-04-07T12:28:54.916Z", "datePublished": "2026-05-01T20:34:22.832Z", "dateUpdated": "2026-05-01T20:34:22.832Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.Bandit.Pipeline'"], "packageName": "bandit", "packageURL": "pkg:hex/bandit", "product": "bandit", "programFiles": ["lib/bandit/pipeline.ex"], "programRoutines": [{"name": "'Elixir.Bandit.Pipeline':determine_scheme/2"}], "repo": "https://github.com/mtrudel/bandit", "vendor": "mtrudel", "versions": [{"lessThan": "1.11.0", "status": "affected", "version": "1.0.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.Bandit.Pipeline'"], "packageName": "mtrudel/bandit", "packageURL": "pkg:github/mtrudel/bandit", "product": "bandit", "programFiles": ["lib/bandit/pipeline.ex"], "programRoutines": [{"name": "'Elixir.Bandit.Pipeline':determine_scheme/2"}], "repo": "https://github.com/mtrudel/bandit", "vendor": "mtrudel", "versions": [{"lessThan": "1.11.0", "status": "affected", "version": "ff2f829326cd5dcf7335939aef9775269d881e28", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>The vulnerable system must be accepting plaintext (non-TLS) HTTP connections, either directly or via h2c. Deployments that exclusively use TLS are not affected.</p>"}], "value": "The vulnerable system must be accepting plaintext (non-TLS) HTTP connections, either directly or via h2c. Deployments that exclusively use TLS are not affected."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.11.0", "versionStartIncluding": "1.0.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "finder", "value": "Peter Ullrich"}, {"lang": "en", "type": "remediation developer", "value": "Mat Trudel"}, {"lang": "en", "type": "analyst", "value": "Jonatan M\u00e4nnchen"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Reliance on Untrusted Inputs in a Security Decision vulnerability in mtrudel bandit allows unauthenticated transport-state spoofing on plaintext HTTP connections.<p><tt>'Elixir.Bandit.Pipeline':determine_scheme/2</tt> in <tt>lib/bandit/pipeline.ex</tt> returns the client-supplied URI scheme verbatim, ignoring the transport's <tt>secure?</tt> flag. HTTP/1.1 absolute-form request targets (e.g. <tt>GET https://victim/path HTTP/1.1</tt>) and the HTTP/2 <tt>:scheme</tt> pseudo-header are both attacker-controlled strings that flow through this function. Over a plaintext TCP connection, a client can declare <tt>https</tt> and Bandit will set <tt>conn.scheme = :https</tt> even though no TLS was negotiated.</p><p>Downstream Plug consumers that branch on <tt>conn.scheme</tt> are silently misled: <tt>Plug.SSL</tt>'s already-secure branch skips its HTTP\u2192HTTPS redirect, cookies emitted with <tt>secure: true</tt> are sent over plaintext, audit logs record requests as having arrived over HTTPS, and CSRF/SameSite gating may make incorrect decisions.</p><p>This issue affects bandit: from 1.0.0 before 1.11.0.</p>"}], "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\u2192HTTPS 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."}], "impacts": [{"capecId": "CAPEC-220", "descriptions": [{"lang": "en", "value": "CAPEC-220 Client-Server Protocol Manipulation"}]}], "metrics": [{"cvssV4_0": {"attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 6.3, "baseSeverity": "MEDIUM", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-807", "description": "CWE-807 Reliance on Untrusted Inputs in a Security Decision", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-05-01T20:34:22.832Z"}, "references": [{"tags": ["vendor-advisory", "related"], "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j"}, {"tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-39807.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-39807"}, {"tags": ["patch"], "url": "https://github.com/mtrudel/bandit/commit/45feea20dea8af7ffd7245271107b695c040e667"}], "source": {"discovery": "EXTERNAL"}, "title": "Client-supplied URI scheme trusted without transport verification in bandit", "x_generator": {"engine": "cvelib 1.8.0"}}}}

{}

{"cveTags": [], "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\u2192HTTPS 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."}], "id": "CVE-2026-39807", "lastModified": "2026-05-01T21:16:17.180", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.3, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}, "published": "2026-05-01T21:16:17.180", "references": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://cna.erlef.org/cves/CVE-2026-39807.html"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/mtrudel/bandit/commit/45feea20dea8af7ffd7245271107b695c040e667"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/mtrudel/bandit/security/advisories/GHSA-375f-4r2h-f99j"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://osv.dev/vulnerability/EEF-CVE-2026-39807"}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-807"}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}

{}