What’s Vulnerable › Vulnerabilities

CVE-2026-45155: Nextcloud: Private circle can be added to another circle via API

• Severity: low (CVSS 2.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-01 · updated 2026-07-22
• Weakness: CWE-639

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

Affected products

• nextcloud security-advisories: from 32.0.0, < 32.0.7; from 33.0.0, < 33.0.1

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

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