CVE-2026-114614VulnerabilityPublished 29 Oct 2026

kaskade · Authlib: is_secure_transport() loopback exemption can be bypassed with a userinfo component, allowing cleartext-HTTP

Affects kaskadeSource GCVE Database

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Authoritative record:CVE-2026-114614· Low 2.6

Not known to be exploited · CVSS 2.6 Low.

Data as of 30 Oct 2026, 08:45 UTC

CVSS 3.1 base score

2.6Low

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	2.6

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Homebrewkaskade`pkg:brew/kaskade`Other threats	Affected >=4.0.4	Fixed in–

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AI-suggested

Until a fix is available, users should avoid relying solely on is_secure_transport() for enforcing TLS on URLs and implement additional validation to reject URLs containing userinfo components with loopback prefixes that do not correspond to actual loopback hosts. Monitoring vendor updates for an official fix is recommended.

Description

Authlib's is_secure_transport() function incorrectly treats URLs with a userinfo component containing loopback prefixes as secure, allowing cleartext HTTP URLs with non-loopback hosts to bypass TLS enforcement. This affects OAuth 2.0 and OIDC endpoint and redirect URI validation, potentially allowing an attacker to register or use URLs that appear secure but actually point to external hosts over HTTP. The issue impacts Authlib versions from 0.13 through 1.7.2. The severity is low due to the nature of the vulnerability being a defense-in-depth and specification conformance failure.

Impact

An attacker able to supply URLs to Authlib components relying on is_secure_transport() can bypass TLS enforcement by using crafted URLs with userinfo containing loopback prefixes but pointing to external hosts over HTTP. This may lead to acceptance of insecure redirect URIs or endpoints in OAuth 2.0 / OIDC flows, potentially enabling redirection to attacker-controlled cleartext HTTP URLs. The impact is limited to defense-in-depth and specification conformance failures, with low severity and no known exploitation in the wild.

Summary

The is_secure_transport() function in Authlib performs a textual prefix check on URLs to enforce TLS usage, with an exemption for loopback HTTP URLs per RFC 8252 §7.3. However, this check uses str.startswith on the full URL string, allowing URLs like http://localhost:80@evil.example/cb to be misclassified as secure because the userinfo component 'localhost:80' matches the loopback prefix. This flaw allows an attacker to supply URLs with userinfo containing loopback prefixes but with an external host and plain HTTP scheme, bypassing TLS enforcement. This affects multiple Authlib components that rely on is_secure_transport() for validating OAuth 2.0 and OIDC URIs, including dynamic client registration, authorization server metadata validation, and error redirect rendering.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 08:45 UTC

Technical details

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