CVE-2026-77164

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Server", "vendor": "Nextcloud", "versions": [{"lessThanOrEqual": "32.0.0", "status": "affected", "version": "31.0.0", "versionType": "semver"}]}], "source": "support@hackerone.com"}], "cveTags": [], "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."}], "id": "CVE-2026-77164", "lastModified": "2026-09-18T20:17:22.273", "metrics": {"cvssMetricV30": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "NONE", "baseScore": 6.2, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "version": "3.0"}, "exploitabilityScore": 2.5, "impactScore": 3.6, "source": "support@hackerone.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-77164", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-09-18T19:40:57.953385Z", "version": "2.0.3"}}]}, "published": "2026-09-18T02:17:07.510", "references": [{"source": "support@hackerone.com", "url": "https://hackerone.com/reports/3303283"}], "sourceIdentifier": "support@hackerone.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-918"}], "source": "support@hackerone.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[31.0.0,32.0.0]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Server", "source": "cna", "vendor": "Nextcloud"}, "product": "server", "vendor": "nextcloud"}], "created": "2026-09-18T11:00:08.916552+00:00", "updated": "2026-09-19T21:45:16.874290+00:00", "vendors": ["nextcloud", "nextcloud$PRODUCT$server"]}