CVE-2026-77164 Server-side request forgery in Server
Unauthenticated attackers can force Nextcloud servers to make internal requests via Circles app, bypassing SSRF protections to probe internal services.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77164?
CVE-2026-77164 is a medium-severity server-side request forgery vulnerability in Nextcloud Server, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-918
Which versions are affected by CVE-2026-77164?
1 open source package ship an affected version, including nextcloud.
| Package | Affected | Fixed in |
|---|---|---|
nextcloud Bitnami | From 31.0.0 | 34.0.1 |
How do I fix CVE-2026-77164?
Upgrade nextcloud to 34.0.1 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-77164 being exploited?
There is no known exploitation of CVE-2026-77164 in the wild and no public exploit code.
Sources
Also known as BIT-nextcloud-2026-77164, GHSA-h4g5-x94v-qxqg.