VulnerabilityPublished 31 Oct 2026

CVE-2026-116672: Mcpm · Authlib RFC 7592 examples omit registration-access-token client binding

Affects mcpmSource GCVE Database

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Authoritative record:CVE-2026-116672· High 8.8

Not known to be exploited · CVSS 8.8 High : upgrade to 2.15.0_5 soon.

Data as of 31 Oct 2026, 16:07 UTC

CVSS 3.1 base score

8.8High

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	8.8

Patch: Available – fixed in 2.15.0_5

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

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

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: None: The vulnerable system can be exploited without any interaction from any user.
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 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 30 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

Upgrade mcpm to 2.15.0_5.

Affected software

Product	Affected	Fixed in
Homebrewmcpm`pkg:brew/mcpm`Other threats	Affected >=2.1.0 <2.15.0_5	Fixed in 2.15.0_5

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AI-suggested

A patch is available in mcpm version 2.15.0_5 that corrects the authorization logic by properly binding the registration_access_token to the client being accessed. Users should upgrade to version 2.15.0_5 or later to remediate this vulnerability. Until patched, developers should avoid using the provided example implementations as-is and ensure that the token is explicitly verified to belong to the client targeted by the request.

Description

CVE-2026-116672 is a vulnerability in Authlib's implementation of the OAuth 2.0 Dynamic Client Registration Management Protocol (RFC 7592). The provided example code for the ClientConfigurationEndpoint fails to bind the registration_access_token to the specific client being accessed, allowing an attacker with any valid token and knowledge of a client_id to bypass authorization and modify or delete client registrations. This flaw arises because the example implementations do not verify that the token belongs to the client targeted by the request. A fix is available in version 2.15.0_5.

Impact

An attacker with any valid registration_access_token and knowledge or guess of a client_id can bypass authorization controls to read, update, or delete client registrations that they do not own. This compromises the integrity and confidentiality of client registration data, potentially allowing unauthorized client impersonation or denial of service by deleting registrations. The CVSS 3.1 score is 8.8 (high), reflecting network attack vector, low complexity, low privileges required, no user interaction, and high impact on confidentiality, integrity, and availability.

Summary

RFC 7592 defines a protocol where a client can manage its own registration using a registration_access_token issued at registration. Authlib's ClientConfigurationEndpoint calls abstract methods for token authentication, client authentication, and permission checking. However, the documented example implementations for authenticate_client and check_permission do not verify that the authenticated token is bound to the client being accessed. This omission leads to an authorization bypass, as possession of any valid registration_access_token and knowledge of a client_id suffices to access or modify that client's registration. The issue contrasts with the correct binding demonstrated in Authlib's RFC 7662 token introspection example. No complete corrected example is provided in the repository. The vulnerability affects mcpm versions >=2.1.0 and <2.15.0_5 and is fixed in 2.15.0_5.

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Affected software

Description

AI analysisMachine-generated, updated 31 Oct 2026, 16:07 UTC

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