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Server · Vulnerability

CVSS 3.0 6.2 MEDIUMCheck source for fixed versionsKEV status unknown

cve-program · CVE-2026-77164

Published

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.

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Affected versions, risk and source history

Exploitation and risk

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cve-program · CVE-2026-77164

Published

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 prot…

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.

Source published
18 Sep 2026 01:26:04 UTC
Source modified
18 Sep 2026 19:41:07 UTC
Saved here
23 Oct 2026 15:48:27 UTC
Source terms
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CVSS 3.0 · 6.2 CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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Sources read 13 Nov 03:01 UTC · 274 of 275 readable · 272 fully read · documentation 469/469 current