Bug 2540975

Summary:	CVE-2026-92288 lemonldap-ng: lemonldap-ng: Information disclosure via unauthenticated OAuth 2.0 token introspection [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Vladimir Vasilev <vvasilev>
Component:	lemonldap-ng	Assignee:	Xavier Bachelot <xavier>
Status:	ON_QA ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	rawhide	CC:	xavier
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["90c8dcec-733d-4c27-b598-0d4e880e14f0"]}
Fixed In Version:		Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2540880

Description Vladimir Vasilev 2026-09-25 07:34:24 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Lemonldap::NG::Portal versions from 2.20.0 before 2.21.6, from 2.22.0 before 2.23.4 for Perl allow unauthenticated OAuth2 token introspection because checkEndPointAuthenticationCredentials does not verify the client secret of a public Relying Party.

checkEndPointAuthenticationCredentials() skips the secret comparison for a Relying Party marked public and still returns the authentication method deduced from the request, client_secret_basic or client_secret_post. introspection() rejects a caller only when that method is missing or none, so a request carrying a public client_id and an arbitrary or empty secret passes the endpoint's authentication check.

An attacker who holds an access token and knows the client_id of any public Relying Party can confirm the token is active and read its metadata, including scope, audience, expiry and the sub claim. The sub claim is computed with the calling Relying Party's user identifier attribute, so an attacker can translate a user identifier from one Relying Party to another, defeating per-client and pseudonymous identifiers.

Comment 1 Fedora Update System 2026-09-25 08:14:14 UTC

FEDORA-2026-76a3490aa6 (lemonldap-ng-2.23.4-1.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-76a3490aa6

Comment 2 Fedora Update System 2026-09-25 08:14:22 UTC

FEDORA-2026-827241e2de (lemonldap-ng-2.23.4-1.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-827241e2de

Comment 3 Fedora Update System 2026-09-25 08:14:30 UTC

FEDORA-2026-33dcab55b4 (lemonldap-ng-2.23.4-1.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-33dcab55b4

Comment 4 Fedora Update System 2026-09-26 01:47:45 UTC

FEDORA-2026-76a3490aa6 has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-76a3490aa6`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-76a3490aa6

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-09-26 02:04:09 UTC

FEDORA-2026-827241e2de has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-827241e2de`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-827241e2de

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2026-09-26 02:27:28 UTC

FEDORA-2026-33dcab55b4 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-33dcab55b4`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-33dcab55b4

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.