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.
No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
| Link | Providers |
|---|---|
| https://hackerone.com/reports/3303283 |
|
Sat, 19 Sep 2026 22:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Title | Blind SSRF in Nextcloud Circles via Remote-Instance Verification |
Sat, 19 Sep 2026 02:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Title | Blind SSRF in Nextcloud Circles via Remote-Instance Verification |
Fri, 18 Sep 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Fri, 18 Sep 2026 11:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Nextcloud
Nextcloud server |
|
| Vendors & Products |
Nextcloud
Nextcloud server |
Fri, 18 Sep 2026 01:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Weaknesses | CWE-918 | |
| References |
| |
| Metrics |
cvssV3_0
|
Projects
Sign in to view the affected projects.
Status: PUBLISHED
Assigner: hackerone
Published:
Updated: 2026-09-18T19:41:07.400Z
Reserved: 2026-08-20T15:00:00.606Z
Link: CVE-2026-77164
Updated: 2026-09-18T19:41:04.281Z
Status : Deferred
Published: 2026-09-18T02:17:07.510
Modified: 2026-09-18T20:17:22.273
Link: CVE-2026-77164
No data.
OpenCVE Enrichment
Updated: 2026-09-19T21:45:16Z