CVE-2026-45156
Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC
Description
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.
INFO
Published Date :
June 1, 2026, 5:17 p.m.
Last Modified :
July 22, 2026, 7:10 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Nextcloud to version 3.1.0 or later.
- Update Nextcloud to version 4.1.0 or later.
- Update Nextcloud to version 5.1.0 or later.
- Update Nextcloud to version 6.4.0 or later.
Public PoC/Exploit Available at Github
CVE-2026-45156 has a 3 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-45156.
| URL | Resource |
|---|---|
| https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp | |
| https://github.com/nextcloud/user_oidc/pull/1285 | |
| https://hackerone.com/reports/3489490 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-45156 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-45156
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
OS Command Injection in Health Check → Remote Code Execution
Shell
This repository contains the Proof of Concept (PoC) exploit script for CVE-2026-45156
Python
📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.
security cve exploit poc vulnerability
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-45156 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-45156 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Jul. 22, 2026
Action Type Old Value New Value Added Translation Title: security-advisories de nextcloud, Description: Nextcloud es una plataforma de colaboración de contenido de código abierto. Desde las versiones 0.3.0 hasta antes de la 3.1.0, 5.0.0 hasta antes de la 5.1.0, y 6.0.0 hasta antes de la 6.4.0, una verificación de firma faltante en User OIDC permitió a una autoridad ID4me maliciosa identificarse como cualquier usuario. Este problema ha sido parcheado en las versiones 3.1.0, 4.1.0, 5.1.0, 6.4.0 y 8.3.0. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'nextcloud', 'product': 'security-advisories', 'versions': [{'status': 'affected', 'version': '>= 0.3.0, < 3.1.0'}, {'status': 'affected', 'version': '>= 5.0.0, < 5.1.0'}, {'status': 'affected', 'version': '>= 6.0.0, < 6.4.0'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-45156', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-02T00:00:00+00:00'} -
New CVE Received by [email protected]
Jun. 01, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N Added CWE CWE-287 Added Reference https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp Added Reference https://github.com/nextcloud/user_oidc/pull/1285 Added Reference https://hackerone.com/reports/3489490