VulnerabilityPublished 29 Oct 2026

CVE-2026-114619: Authlib · OpenID implicit grant checks raw scope instead of allowed scope before issuing ID tokens

Affects kaskadeSource GCVE Database

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Authoritative record:CVE-2026-114619· Medium 4.6

Not known to be exploited · CVSS 4.6 Medium · fixed in 1.8.0 : update kaskade when convenient.

Data as of 30 Oct 2026, 08:45 UTC

CVSS 3.1 base score

4.6Medium

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	4.6

Patch: Available – fixed in 1.8.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: Low
Integrity: Low
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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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

A fix is available in Authlib version 1.8.0 (commit c529a61af40e3efe05286140e00fbdced07d7987) where this issue was identified and verified. Users should upgrade to this or a later version that includes the fix. If upgrading is not immediately possible, ensure that clients permitted 'id_token' or 'id_token token' response types are also explicitly allowed the 'openid' scope to prevent exploitation. Deployments that use only the authorization code flow are not affected by this vulnerability. No other mitigation actions are indicated by the vendor advisory.

Description

Authlib's OpenID Connect implicit grant implementation contains a vulnerability where it checks the raw client-supplied scope instead of the filtered allowed scope before issuing ID tokens. This allows a registered OAuth client that is not permitted the 'openid' scope but allowed other scopes like 'profile' to obtain a signed ID token if the user consents. The ID token includes identity claims such as 'sub' and 'name', effectively bypassing intended scope restrictions. This issue affects deployments using the OpenID implicit grant and clients permitted 'id_token' response types but not the 'openid' scope. The vulnerability does not affect authorization code flow deployments or those where clients with 'id_token' response types are also allowed the 'openid' scope.

Impact

A registered OAuth client that is not allowed the 'openid' scope but permitted 'id_token' response types can obtain a signed OpenID Connect ID token for any user who logs in and consents. This ID token contains identity claims such as the user's subject identifier and profile information, effectively bypassing scope restrictions intended to prevent unauthorized issuance of identity tokens. The access token remains scope-restricted and is rejected by the UserInfoEndpoint. The vulnerability could lead to unauthorized disclosure of user identity information to clients not authorized for the 'openid' scope. However, exploitation requires the client to be registered with specific permissions and user consent, limiting the practical impact. Deployments using only the authorization code flow or where clients with 'id_token' response types are also allowed 'openid' are not affected.

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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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