{"id":"CVE-2026-77164","state":"PUBLISHED","title":"Circles' remote-instance signature verification fetches the attacker-supplied keyId URL before trust in the remote instance is established, and explicitly allows local/private addr","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.\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.","publishedAt":"2026-09-18T01:26:04.650Z","updatedAt":"2026-09-18T19:41:07.400Z","severity":{"score":6.2,"label":"Medium","version":"3.0","vector":"CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","source":"hackerone"},"assigner":"hackerone","products":["Nextcloud Server"],"affected":[{"vendor":"Nextcloud","product":"Server","defaultStatus":"unaffected","versions":[{"version":"31.0.0","status":"affected","lessThanOrEqual":"32.0.0","versionType":"semver"}]}],"references":["https://hackerone.com/reports/3303283"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77164.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77164","state":"PUBLISHED","datePublished":"2026-09-18T01:26:04.650Z","dateUpdated":"2026-09-18T19:41:07.400Z","assignerShortName":"hackerone","assignerOrgId":"36234546-b8fa-4601-9d6f-f4e334aa8ea1","dateReserved":"2026-08-20T15:00:00.606Z"},"containers":{"cna":{"descriptions":[{"lang":"en","value":"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.\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."}],"affected":[{"vendor":"Nextcloud","product":"Server","defaultStatus":"unaffected","versions":[{"version":"31.0.0","status":"affected","lessThanOrEqual":"32.0.0","versionType":"semver"}]}],"references":[{"url":"https://hackerone.com/reports/3303283"}],"metrics":[{"cvssV3_0":{"version":"3.0","vectorString":"CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","baseScore":6.2,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","type":"CWE","lang":"en","description":"CWE-918 Server-Side Request Forgery (SSRF)"}]}],"providerMetadata":{"shortName":"hackerone","orgId":"36234546-b8fa-4601-9d6f-f4e334aa8ea1","dateUpdated":"2026-09-18T01:26:04.650Z"},"credits":[{"lang":"en","value":"Balvant Chavda (0x0doteth)","type":"finder"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-18T19:40:57.953385Z","id":"CVE-2026-77164","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-18T19:41:07.400Z"}}]}}}