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OpenAdvisories
High WID-SEC-2026-1471 19 CVEs

Nextcloud: Mehrere Schwachstellen

Published May 11, 2026 · Updated Jun 1, 2026 · Revision 2 · de-DE

Vendor: Nextcloud Product: Nextcloud Platform: Linux Platform: Windows

Summary

Ein Angreifer kann mehrere Schwachstellen im Nextcloud Server und verschiedenen Apps ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um Informationen offenzulegen, und um Dateien zu manipulieren.

Product

Nextcloud ist eine "on-premise" Plattform für Dateifreigabe und Zusammenarbeit.

Vulnerabilities 19

  • High 8.1
    CVE-2026-45156 Public exploit

    Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC

    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 …

    Nextcloud security-advisories
  • High 8.1
    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 …

    Nextcloud security-advisories
  • Medium 6.5
    CVE-2026-45267

    Nextcloud: Missing permission check for from submissions

    Nextcloud is an open source content collaboration platform. Prior to version 5.2.6, a missing permissions check allowed users to request reading form submissions of other users. This issue has been patched in version 5.2.6.

    Nextcloud security-advisories
  • Medium 6.5
    CVE-2026-45275

    Nextcloud: Authorization bypass in approval feature allows unauthorized file sharing with approvers

    Nextcloud is an open source content collaboration platform. Prior to version 2.7.2, a privilege escalation vulnerability exists in the Approval app that allows a user without sharing permissions to force the system to share a file with approvers. This results…

    Nextcloud security-advisories
  • Medium 6.5
    CVE-2026-45282

    Nextcloud: Logged-in user bypasses share password and download restrictions on Text attachments via documentId leads to unauthorized file access

    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, an authenticated attacker can access attachments of link shares when knowing the share token, circumventing pas…

    Nextcloud security-advisories
  • Medium 6.4
    CVE-2026-45285

    Nextcloud: Hidden Public Link creation when sharing to a Team External Member

    Nextcloud is an open source content collaboration platform. From versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, when a user shares a folder or file with a Nextcloud Team that includes an external member (a person added via email address who do…

    Nextcloud security-advisories
  • Medium 6.3
    CVE-2026-45157

    Nextcloud: Valid share tokens allow to access tempory upload files of share owner

    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, when a malicious user has access to a file share of a user, they could use this share token to also access the …

    Nextcloud security-advisories
  • Medium 6.3
    CVE-2026-45283

    Nextcloud: Files Lock app allows users to lock and unlock files of other users

    Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.2, and 33.0.0 to before 33.0.1, the files_lock app did not properly validate the ownership of files when processing DAV lock and unlock request…

    Nextcloud security-advisories
  • Medium 4.6
    CVE-2026-45153

    Nextcloud: PIN bypass in PassCodeActivity via back button

    Nextcloud is an open source content collaboration platform. From version 33.0.0 to before version 33.1.0, after unlocking a locked Android phone the back-button could be used to bypass the Nextcloud Files app PIN. This issue has been patched in version 33.1.0.

    Nextcloud security-advisories
  • Medium 4.6
    CVE-2026-45284

    Nextcloud: Wrong condition in the User OIDC app's LdapService allowed deleted LDAP users to authenticate

    Nextcloud is an open source content collaboration platform. From version 1.3.6 to before version 8.4.0, an improper check allowed users that where provided by LDAP to still authenticate towards user OIDC after they where deleted. This issue has been patched i…

    Nextcloud security-advisories
  • Medium 4.4
    CVE-2026-45279

    Nextcloud: Limited path traversal via template API if using `{lang}` in config

    Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 31.0.0 to before 31.0.14, and 32.0.0 to before 32.0.4, if {lang} is used in the template directory config value, non-admin users can in some cases copy arbitrary fil…

    Nextcloud security-advisories
  • Medium 4.3
    CVE-2026-45264

    Nextcloud: ACL Rename Permission Bypass in Team Folders Allows Unauthorized File Renames

    Nextcloud is an open source content collaboration platform. From versions 17.0.0 to before 17.0.15, 18.0.0 to before 18.1.12, 19.0.0 to before 19.1.16, 20.0.0 to before 20.1.11, and 21.0.0 to before 21.0.4, a user with READ and CREATE permission, but no UPDAT…

    Nextcloud security-advisories
  • Medium 4.3
    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 attendee…

    Nextcloud security-advisories
  • Low 3.5
    CVE-2026-45159

    Nextcloud: Files drop share links for end-to-end encrypted folders allowed to drop files into other folders of the share owner

    Nextcloud is an open source content collaboration platform. From versions 1.15.0 to before 1.15.4, 1.16.0 to before 1.16.3, 1.17.0 to before 1.17.1, and 1.18.0 to before 1.18.1, a malicious user with access to an end-to-end encrypted files drop link was able …

    Nextcloud security-advisories
  • Low 3.5
    CVE-2026-45266

    Nextcloud: Unauthorized force-mute from missing permission check when using internal signaling

    Nextcloud is an open source content collaboration platform. Prior to versions 21.1.10, 22.0.11, and 23.0.3, a low-privileged user can force other user's microphones to be muted in calls when no High-performance Backend is installed. This issue has been patche…

    Nextcloud security-advisories
  • Low 3.3
    CVE-2026-45277

    Nextcloud: Information disclosure in Nextcloud Approval app via fileId parameter reveals workflow associations

    Nextcloud is an open source content collaboration platform. Prior to version 2.7.2, authenticated users can check if arbitrary files are associated with specific approval workflows where they can request approval. This issue has been patched in version 2.7.2.

    Nextcloud security-advisories
  • Low 3.3
    CVE-2026-45278

    Nextcloud: Open Redirect in user_oidc login flow via protocol-relative URL bypass

    Nextcloud is an open source content collaboration platform. From version 6.1.0 to before version 8.2.2, an attacker can craft links that would redirect users to another website, when the victim uses the attackers link to log in via user OIDC. This issue has b…

    Nextcloud security-advisories
  • Low 2.6
    CVE-2026-45154

    Nextcloud: Improper Access Control in Collectives

    Nextcloud is an open source content collaboration platform. From version 2.6.0 to before version 4.3.0, when a previous collective pages was deleted and the collective was shared view-only, guests with access to the collective were able to access the deleted …

    Nextcloud security-advisories
  • Low 2.6
    CVE-2026-45155

    Nextcloud: Private circle can be added to another circle via API

    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 …

    Nextcloud security-advisories

Revision history

  1. #2

    Referenz(en) aufgenommen: EUVD-2026-33677, EUVD-2026-33676, EUVD-2026-33675, EUVD-2026-33674, EUVD-2026-33673, EUVD-2026-33671, EUVD-2026-33678, EUVD-2026-33711, EUVD-2026-33710, EUVD-2026-33709, EUVD-2026-33708, EUVD-2026-33707, EUVD-2026-33706, EUVD-2026-33705, EUVD-2026-33704, EUVD-2026-33703, EUVD-2026-33702, EUVD-2026-33679, EUVD-2026-33672

  2. #1

    Initiale Fassung

References