This Week in Spring - June 2nd, 2026

Hi, Spring fans, and welcome to another momentous installment of This Week in Spring! A lot to get into this week, but let's first take some time to address the meta: where are the May releases? If you read our May 11th post, you know they've been delayed. We wanted to speak a bit more about why ...

CVE-2026-45281

A flaw was found in Nextcloud Server. An authenticated user, with knowledge of another user's principal URL, could exploit improper authorization controls to gain full access to that user's calendar. This allows the attacker to view and modify the victim's calendar, leading to unauthorized...

CVE-2026-45286

Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied t...

CVE-2026-45281

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the...

CVE-2026-45286 Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint

Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied t...

EUVD-2026-33711

Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied t...

CVE-2026-45286 Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint

Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied t...

CVE-2026-45286

CVE-2026-45286 affects Nextcloud Open Source Content Collaboration Platform. An authenticated user could enumerate other users on the same instance by abusing the Calendar app’s endpoint for suggesting attendees; standard sharing restrictions did not apply to that endpoint. Impacted versions are ...

CVE-2026-45286

Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied t...

CVE-2026-45286 Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint

Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied t...

CVE-2026-45281 Nextcloud: Cross-Account Calendar Takeover via Unauthorized Group-Member-Set Update

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the...

CVE-2026-45281

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the...

CVE-2026-45281

CVE-2026-45281 affects Nextcloud Server versions 32.0.0–32.0.8 and 33.0.0–33.0.2. The issue stems from improper authorization in the calendar backend, requiring an authenticated attacker who knows another user’s principal URL. An authenticated user could potentially send a request to gain full ac...

CVE-2026-45281 Nextcloud: Cross-Account Calendar Takeover via Unauthorized Group-Member-Set Update

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the...

EUVD-2026-33706

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the...

CVE-2026-45281 Nextcloud: Cross-Account Calendar Takeover via Unauthorized Group-Member-Set Update

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the...

PT-2026-45530

Name of the Vulnerable Software and Affected Versions Nextcloud versions 5.5.13 through 5.5.16 Nextcloud versions 6.2.0 through 6.2.2 Description An authenticated user can enumerate other users on the same instance. This is possible because sharing restrictions were not effectively applied to the...

PT-2026-45525

Name of the Vulnerable Software and Affected Versions Nextcloud Server versions 32.0.0 through 32.0.8 Nextcloud Server versions 33.0.0 through 33.0.2 Nextcloud Enterprise Server versions prior to 33.0.3 Nextcloud Enterprise Server versions prior to 32.0.9 Nextcloud Enterprise Server versions prio...

Nextcloud Server 安全漏洞

NextCloud Server is an open-source NextCloud server program developed by NextCloud. There were security vulnerabilities in versions 32.0.0 to 32.0.9 and 33.0.0 to 33.0.3 of NextCloud Server. These vulnerabilities stemmed from improper authorization control in the calendar backend, allowing...

Nextcloud Calendar 信息泄露漏洞

NextCloud Calendar is an open-source calendar application developed by NextCloud. There were information leakage vulnerabilities in versions 5.5.13 to 5.5.17 and 6.2.0 to 6.2.3 of NextCloud Calendar. These vulnerabilities stemmed from the lack of shared restrictions applied to the meeting...