Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover

{
  "id": "6e8286849f5f781ea9aef383810471abb6a60c9e2b560eedba464cc8e3892622",
  "url": "https://osv.dev/vulnerability/GHSA-xv7q-fvmc-jx96",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover",
    "summary": "## Summary With the per-provider OIDC `emailfallback` option enabled, Vikunja links an SSO login to a pre-existing **local** (username+password) account using only the `email` claim — no `email_verified` (or Microsoft `xms_edov`) check and no password check, on the unauthenticated callback. An attacker who can make the configured issuer emit a token bearing a victim's email logs in as that victim with a full session and no victim interaction (the nOAuth / Grafana CVE-2023-3128 class). The 2.3.0 fix for GHSA-8jvc-mcx6-r4cg added a TOTP gate, not an `email_verified` gate, so users without TOTP remain exposed. ## Details References are `pkg/modules/auth/openid/openid.go` at HEAD. Identity is first resolved on the immutable `(issuer, subject)` pair (`openid.go:428`). On a subject miss with `emailfallback` on, `fallbackSearchUsers` adds an email-only lookup against local accounts: ```go // openid.go:413 searches = append(searches, &user.User{Issuer: user.IssuerLocal, Email: cl.Email}) ``` `getUser` resolves this via `s.Get()`, which ANDs non-zero fields -> `WHERE issuer='local' AND email=?`. Local users always have `Issuer=\"local\"` (`user_create.go:38`), so the lookup matches any local account by email alone; `getOrCreateUser` returns it and the caller mints a session — the password is never read. The `claims` struct has no `email_verified` field (`openid.go:80`) and `getClaims` never consults one; a repo-wide grep for `email_verified`/`xms_edov` returns nothing. The code already ",
    "evidence": "osv:GHSA-xv7q-fvmc-jx96",
    "products": [
      {
        "name": {
          "value": "code.vikunja.io/api",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-xv7q-fvmc-jx96",
      "aliases": [
        "CVE-2026-62367",
        "GHSA-xv7q-fvmc-jx96",
        "GO-2026-6758"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "1.0.0"
                },
                {
                  "fixed": "2.4.0"
                }
              ]
            }
          ],
          "package": {
            "name": "code.vikunja.io/api",
            "purl": "pkg:golang/code.vikunja.io/api",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-xv7q-fvmc-jx96/GHSA-xv7q-fvmc-jx96.json",
            "last_known_affected_version_range": "<= 2.3.0"
          }
        }
      ],
      "modified": "2026-10-19T21:40:54.288683723Z",
      "provider": "osv",
      "references": [
        "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xv7q-fvmc-jx96",
        "https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630",
        "https://github.com/go-vikunja/vikunja",
        "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-287",
          "CWE-290",
          "CWE-345"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-09T20:49:06Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-62367",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 376751,
  "published_at": "2026-10-09T20:49:06+00:00"
}