CVE-2026-39807

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Source
https://cve.org/CVERecord?id=CVE-2026-39807
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39807.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-39807
Aliases
Published
2026-05-01T20:34:22.832Z
Modified
2026-07-08T08:13:03.234086494Z
Severity
  • 6.3 (Medium) CVSS_V4 - 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 CVSS Calculator
Summary
Client-supplied URI scheme trusted without transport verification in bandit
Details

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.

Database specific 
{
    "unresolved_ranges": [
        {
            "source": "AFFECTED_FIELD",
            "extracted_events": [
                {
                    "introduced": "ff2f829326cd5dcf7335939aef9775269d881e28"
                },
                {
                    "fixed": "45feea20dea8af7ffd7245271107b695c040e667"
                }
            ]
        }
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39807.json",
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-807"
    ]
}
References

Affected packages

Git / github.com/mtrudel/bandit

Affected ranges

Type
GIT
Repo
https://github.com/mtrudel/bandit
Events
Introduced
124d697c3c604aca9122332a4ea789561b925f2e
Fixed
e62619895d0d2584d7ffa57d43ef6f72437dfaff
Fixed
45feea20dea8af7ffd7245271107b695c040e667
Database specific 
{
    "source": [
        "DESCRIPTION",
        "REFERENCES"
    ],
    "extracted_events": [
        {
            "introduced": "1.0.0"
        },
        {
            "fixed": "1.11.0"
        }
    ]
}

Affected versions

1.*
1.0.0
1.1.0
1.1.1
1.1.2
1.1.3
1.10.0
1.10.1
1.10.2
1.10.3
1.10.4
1.2.0
1.2.3
1.3.0
1.4.0
1.4.1
1.4.2
1.5.0
1.5.1
1.5.2
1.5.3
1.5.4
1.5.5
1.5.6
1.5.7
1.6.0
1.6.1
1.6.10
1.6.11
1.6.2
1.6.3
1.6.4
1.6.5
1.6.6
1.6.7
1.6.8
1.6.9
1.7.0
1.8.0
1.9.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39807.json"