Nextcloud Server up to 32.0.0 Circles server-side request forgery

Summaryinfo

A vulnerability classified as problematic has been found in Nextcloud Server up to 32.0.0. Affected is an unknown function of the component Circles. This manipulation causes server-side request forgery. The identification of this vulnerability is CVE-2026-77164. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Nextcloud Server up to 32.0.0. It has been declared as problematic. Affected by this vulnerability is some unknown processing of the component Circles. The manipulation with an unknown input leads to a server-side request forgery vulnerability. The CWE definition for the vulnerability is CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. As an impact it is known to affect confidentiality. The summary by CVE is:

Circles' remote-instance signature verification fetches the attacker-supplied keyId URL before trust in the remote instance is established, and explicitly allows local/private addresses for this request, bypassing Nextcloud's core SSRF protections. The public, unauthenticated endpoints POST /apps/circles/event/ and POST /apps/circles/incoming/ reach this code path, allowing any unauthenticated user to force the server to issue a GET request to an internal address. The response body of the internal request is never returned to the requester, so this is blind SSRF: an attacker can determine whether an internal service is reachable, but cannot read its response contents through this endpoint alone.

The advisory is shared at hackerone.com. This vulnerability is known as CVE-2026-77164 since 08/20/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/18/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-82621). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Cloud Software

Vendor

• Nextcloud

Name

• Server

Version

• 32.0

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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