Nextcloud User OIDC up to 3.0.x/5.0.x/6.3.x ID4me improper authentication

CVSS Meta Temp Score
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CTI Interest Score
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7.0$0-$5k0.00

Summaryinfo

A vulnerability labeled as critical has been found in Nextcloud User OIDC up to 3.0.x/5.0.x/6.3.x. The affected element is an unknown function of the component ID4me Handler. The manipulation results in improper authentication. This vulnerability is reported as CVE-2026-45156. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Nextcloud User OIDC up to 3.0.x/5.0.x/6.3.x. It has been classified as critical. Affected is an unknown part of the component ID4me Handler. The manipulation with an unknown input leads to a improper authentication vulnerability. CWE is classifying the issue as CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Nextcloud is an open source content collaboration platform. From versions 0.3.0 to before 3.1.0, 5.0.0 to before 5.1.0, and 6.0.0 to before 6.4.0, a missing signature verification in User OIDC allowed a malicious ID4me authority to identify as any user. This issue has been patched in versions 3.1.0, 4.1.0, 5.1.0, 6.4.0 and 8.3.0.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-45156 since 05/08/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

Upgrading to version 3.1.0, 5.1.0 or 6.4.0 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.2
VulDB Meta Temp Score: 7.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 8.1
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper authentication
CWE: CWE-287
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: User OIDC 3.1.0/5.1.0/6.4.0
Patch: github.com

Timelineinfo

05/08/2026 CVE reserved
06/01/2026 +24 days Advisory disclosed
06/01/2026 +0 days VulDB entry created
06/01/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-qqgv-fqwp-mjpp
Status: Confirmed

CVE: CVE-2026-45156 (🔒)
GCVE (CVE): GCVE-0-2026-45156
GCVE (VulDB): GCVE-100-367692

Entryinfo

Created: 06/01/2026 20:10
Changes: 06/01/2026 20:10 (67)
Complete: 🔍
Cache ID: 216::103

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