CVE-2026-45155

Description

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.7 and 33.0.0 to before 33.0.1, a missing access check on API level allowed to add unknown circles by their ID directly to other circles. Since circle IDs have 62^15 complexity by default this is still unlikely to be executable at will, but if access to an ID was available via another source, memberships could be tracked like this. It is recommended that the Nextcloud Server is upgraded to 32.0.7 or 33.0.1. It is recommended that the Nextcloud Enterprise Server is upgraded to 29.0.16.14, 30.0.17.8, 31.0.14.3, 32.0.7 or 33.0.1

CVSS v3.1 Score

2.6

LOW

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

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-639 CWE-639

References

Other References

https://github.com/nextcloud/circles/pull/2401 https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xpgv-grf9-gm7x https://hackerone.com/reports/3511998

Frequently Asked Questions

What is CVE-2026-45155? +

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.7 and 33.0.0 to before 33.0.1, a missing access check on API level allowed to add unknown circles by their ID directly to other circles. Since circle IDs have 62^15 complexity by default this is still unlikely to be executable at will, but if access to an ID was available via another source, memberships could be tracked like this. It is recommended that the Nextcloud Server is upgraded to 32.0.7 or 33.0.1. It is recommended that the Nextcloud Enterprise Server is upgraded to 29.0.16.14, 30.0.17.8, 31.0.14.3, 32.0.7 or 33.0.1 It has a CVSS v3.1 base score of 2.6 (LOW).

How severe is CVE-2026-45155? +

CVE-2026-45155 has a CVSS v3.1 score of 2.6 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-45155? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-40570

FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.213, the `load_customer_info` action in `POST /conversation/ajax` …

CVE-2026-9152

A missing authentication vulnerability exists in the Altium 365 SearchService. A legacy SOAP endpoint exposes search index operations without requiring …

CVE-2026-40866

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in …

CVE-2026-40865

Horilla is a free and open source Human Resource Management System (HRMS). In 1.5.0, an insecure direct object reference in …

CVE-2026-6375

A vulnerability in SpiceJet’s booking API allows unauthenticated users to query passenger name records (PNRs) without any access controls. Because …

CVE-2025-15626

Authenticated user can bypass authorization in Ribblr - Crochet & Knitting iOS application