Nextcloud Desktop: Initialization vector reuse in E2EE allows malicious server admin to break, manipulate, access files

{
  "id": "d6e49778a7a999b448ac7a7185d09be9bb9a13d192ded8f8e337a502e089b2c4",
  "url": "https://osv.dev/vulnerability/CVE-2023-28997",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Nextcloud Desktop: Initialization vector reuse in E2EE allows malicious server admin to break, manipulate, access files",
    "summary": "The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server. Starting with version 3.0.0 and prior to version 3.6.5, a malicious server administrator can recover and modify the contents of end-to-end encrypted files. Users should upgrade the Nextcloud Desktop client to 3.6.5 to receive a patch. No known workarounds are available.",
    "evidence": "osv:CVE-2023-28997",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2023-28997",
      "aliases": [
        "CVE-2023-28997",
        "GHSA-4p33-rw27-j5fc"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nextcloud/desktop",
              "type": "GIT",
              "events": [
                {
                  "introduced": "ff175088a391007b66bfca89ef35cf29e37cf001"
                },
                {
                  "fixed": "b128a778253de91443de5f57f2421963515cd469"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "3.0.0"
                      },
                      {
                        "fixed": "3.6.5"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:nextcloud:desktop:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.0.0"
                      },
                      {
                        "fixed": "3.6.5"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-28997.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.624054820Z",
      "provider": "osv",
      "references": [
        "https://ethz.ch/content/dam/ethz/special-interest/infk/inst-infsec/appliedcrypto/education/theses/report_DanieleCoppola.pdf",
        "https://lists.debian.org/debian-lts-announce/2025/09/msg00018.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/28xxx/CVE-2023-28997.json",
        "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-4p33-rw27-j5fc",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-28997",
        "https://github.com/nextcloud/desktop/pull/5324"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-323"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/28xxx/CVE-2023-28997.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-28997",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497552,
  "published_at": "2023-04-04T12:42:24.54+00:00"
}