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

CVSS 8.1 · High

Affected Version Matrix 2

VendorProductVersion RangeStatus
nextcloudsecurity-advisories>= 32.0.0, < 32.0.9affected
>= 33.0.0, < 33.0.3affected
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I. Basic Information for CVE-2026-45281

Vulnerability Information
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Vulnerability Title
Nextcloud: Cross-Account Calendar Takeover via Unauthorized Group-Member-Set Update
Source: NVD (National Vulnerability Database)
Vulnerability Description
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 attacker must be an authenticated user. This is because of improper authorization controls in the backend of the calendar. If the attacker had access to the calendar, they would be able to view and modify it. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, 29.0.16.16, 28.0.14.17, 27.1.11.26, 26.0.13.26, 25.0.13.29, 24.0.12.34, 23.0.12.35, 22.2.10.39, or 21.0.9.23
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
通过用户控制密钥绕过授权机制
Source: NVD (National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
nextcloudsecurity-advisories >= 32.0.0, < 32.0.9 -

II. Public POCs for CVE-2026-45281

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III. Intelligence Information for CVE-2026-45281

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Patches & Fixes for CVE-2026-45281 (1)

Vendor Advisories for CVE-2026-45281 (1)

Same Patch Batch · nextcloud · 2026-06-01 · 26 CVEs total

CVE-2026-455458.2 HIGHNextcloud: SQL Injection in Column Type Parameter Allows Arbitrary SQL Execution
CVE-2026-451568.1 HIGHNextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification
CVE-2026-457227.1 HIGHNextcloud: Tables app allows limited SQLi in ORDER BY with malicious sort order argument f
CVE-2026-458106.8 MEDIUMNextcloud: Propfind requests for file comments allowed to load comments for other files
CVE-2026-452756.5 MEDIUMNextcloud: Authorization bypass in approval feature allows unauthorized file sharing with
CVE-2026-452826.5 MEDIUMNextcloud: Logged-in user bypasses share password and download restrictions on Text attach
CVE-2026-452676.5 MEDIUMNextcloud: Missing permission check for from submissions
CVE-2026-452856.4 MEDIUMNextcloud: Hidden Public Link creation when sharing to a Team External Member
CVE-2026-452836.3 MEDIUMNextcloud: Files Lock app allows users to lock and unlock files of other users
CVE-2026-451576.3 MEDIUMNextcloud: Valid share tokens allow to access tempory upload files of share owner
CVE-2026-456905.9 MEDIUMNextcloud: Two-Factor Authentication Bypass via Pending Session Token Replay
CVE-2026-456915.9 MEDIUMNextcloud: Bypass of second factor authentication on DAV endpoints
CVE-2026-455435.3 MEDIUMNextcloud: Deleting a Forms collaborator share leaves uploaded response files accessible t
CVE-2026-451534.6 MEDIUMNextcloud: PIN bypass in PassCodeActivity via back button
CVE-2026-452844.6 MEDIUMNextcloud: Wrong condition in the User OIDC app's LdapService allowed deleted LDAP users t
CVE-2026-452794.4 MEDIUMNextcloud: Limited path traversal via template API if using `{lang}` in config
CVE-2026-452644.3 MEDIUMNextcloud: ACL Rename Permission Bypass in Team Folders Allows Unauthorized File Renames
CVE-2026-452864.3 MEDIUMNextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint
CVE-2026-455444.3 MEDIUMNextcloud: Information Disclosure of view filter metdata via Broken Sensitive Data Masking
CVE-2026-451593.5 LOWNextcloud: Files drop share links for end-to-end encrypted folders allowed to drop files i

Showing top 20 of 26 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: security-advisories
Same vendor: nextcloud
Same weakness: CWE-639

V. Comments for CVE-2026-45281

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