CVE-2026-77164: Nextcloud Server vulnerability
Nextcloud · Server
Affected: Nextcloud Server · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 8% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- Nextcloud · Serverfrom 31.0.0 up to and including 32.0.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Weakness
- Server-Side Request Forgery
- Vendor
- Nextcloud
- Published
- September 2026
- Bounty reports
- 1 disclosed on HackerOne
Disclosed bug bounty reports about CVE-2026-77164
The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.
- Unauthenticated blind SSRF in Circles signature verification bypasses Nextcloud local-address protectionsNextcloud · 2026 · medium severityValid
CoverageNo articles yet
No CyberSIXT article names CVE-2026-77164 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.