Membership tracking via unchecked circle identifiers
Published Jun 1, 2026 · Updated Jun 1, 2026
Authorization bypass in Nextcloud Server 32.0.0 through 32.0.6 and 33.0.0 allows remote authenticated users to track circle memberships. The Circles API memberAdd and membersAdd paths accept a circle member ID and call addMember without first using getCircle to enforce visibility access for circle-type members. Exploitation requires low-privileged access, user interaction, and a valid 15-character circle ID obtained elsewhere; the reported consequence is membership disclosure only.
Summary
What happened
Authorization bypass in Nextcloud Server 32.0.0 through 32.0.6 and 33.0.0 allows remote authenticated users to track circle memberships. The Circles API memberAdd and membersAdd paths accept a circle member ID and call addMember without first using getCircle to enforce visibility access for circle-type members. Exploitation requires low-privileged access, user interaction, and a valid 15-character circle ID obtained elsewhere; the reported consequence is membership disclosure only.
The record
- CVE
- CVE-2026-45155
- Published
- Jun 1, 2026
- Updated
- Jun 1, 2026
- Vendor
- Nextcloud GmbH
- Product
- Security Advisories
- Classifications
- CWE-639, T1069
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 1, 2026CVE publishedPublication date reported by the CVE source.
- Jun 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 32.0.0, < 32.0.7
- Affected versionversion=>= 33.0.0, < 33.0.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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