Vikunja: Unbounded CSV row cardinality permits API process termination

{
  "id": "93438b798ede3fd6fe81e1bad885105b828d5db71a3dad67711c9518f2b620e2",
  "url": "https://osv.dev/vulnerability/GHSA-pqf9-h8g4-8gmh",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Vikunja: Unbounded CSV row cardinality permits API process termination",
    "summary": "# Unbounded CSV row cardinality permits API process termination ## Summary The authenticated v2 CSV migration route caps upload bytes but not parsed row cardinality. It reads every record into a [][]string and then materializes a full task object for every row before insertion. Two million one-cell rows fit in a roughly 4 MB multipart request yet exhaust a 512 MiB API process. ## Impact and affected scope - **Type:** Resource Exhaustion Csv Import - **Affected component:** POST /api/v2/migration/csv/migrate - **Preconditions:** An ordinary authenticated user supplies a multipart CSV containing a very large number of tiny records plus a valid mapping configuration. - **Verified revision:** `349cd5adbcc831ef08b08e6c9c6d627603c39606` on 28 August 2026 - **Affected release range:** `= 2.5.0`; broader historical range not established and maintainer confirmation requested A low-privileged remote user can terminate the API process and deny service to all users with a request far below the configured upload-byte limit. ## Technical details csv.Reader.ReadAll retains every row, after which convertToVikunja allocates a task structure for each row; the existing upload-byte cap does not constrain this cardinality amplification. Attack path: Authenticate, upload two million one-cell records to the synchronous CSV migrate route with a valid ignore mapping, and exhaust process memory while parsing and materializing rows. Relevant code: - `pkg/routes/api/v2/migration_csv.go:96` - `pkg/routes",
    "evidence": "osv:GHSA-pqf9-h8g4-8gmh",
    "products": [
      {
        "name": {
          "value": "code.vikunja.io/api",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.6.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.5.0",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-pqf9-h8g4-8gmh",
      "aliases": [
        "CVE-2026-91969",
        "GHSA-pqf9-h8g4-8gmh",
        "GO-2026-6746"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "2.5.0"
                },
                {
                  "fixed": "2.6.0"
                }
              ]
            }
          ],
          "package": {
            "name": "code.vikunja.io/api",
            "purl": "pkg:golang/code.vikunja.io/api",
            "ecosystem": "Go"
          },
          "versions": [
            "2.5.0"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-pqf9-h8g4-8gmh/GHSA-pqf9-h8g4-8gmh.json"
          }
        }
      ],
      "modified": "2026-10-19T21:41:11.410769661Z",
      "provider": "osv",
      "references": [
        "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-pqf9-h8g4-8gmh",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-91969",
        "https://github.com/go-vikunja/vikunja/pull/3688",
        "https://github.com/go-vikunja/vikunja",
        "https://github.com/go-vikunja/vikunja/releases/tag/v2.6.0",
        "https://www.vulncheck.com/advisories/vikunja-before-2.6.0-resource-exhaustion-via-csv-migration"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-400"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-09T20:53:14Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-91969",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 376781,
  "published_at": "2026-10-09T20:53:14+00:00"
}