CVE-2026-77164

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