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CVE-2026-77164 (GCVE-0-2026-77164)

Vulnerability from cvelistv5 – Published: 2026-09-18 01:26 – Updated: 2026-09-18 01:26
VLAI
Summary
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.
Severity
6.2 (Medium)
CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE
  • CWE-918 - Server-Side Request Forgery (SSRF)
Assigner
References
Impacted products
Vendor Product Version CPE status
Nextcloud Server Affected: 31.0.0 , ≤ 32.0.0 (semver)
guessed Create a notification for this product.
Credits
Balvant Chavda (0x0doteth)
Show details on NVD website
To clipboard 

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          "type": "finder",
          "value": "Balvant Chavda (0x0doteth)"
        }
      ],
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        {
          "lang": "en",
          "value": "Circles\u0027 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\u0027s 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.\n\nThe 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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        "cveTags": [],
        "descriptions": [
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            "value": "Circles\u0027 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\u0027s 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.\n\nThe 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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                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
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                "vectorString": "CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
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}



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