Vulnerability · Published Jun 1, 2026 · Assigned by GitHub_M
CVE-2026-45155Nextcloud: Private circle can be added to another circle via API
Low 2.6
In plain English
A low-severity authorization bypass via user-controlled key in security-advisories from nextcloud. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nextcloud | security-advisories | >= 32.0.0, < 32.0.7>= 33.0.0, < 33.0.1 |
Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
References
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xpgv-grf9-gm7x x_refsource_CONFIRM
- https://github.com/nextcloud/circles/pull/2401 x_refsource_MISC
- https://hackerone.com/reports/3511998 x_refsource_MISC