Vulnerability-Lookup

CVE-2026-62367 (GCVE-0-2026-62367)

Vulnerability from cvelistv5 – Published: 2026-10-09 20:49 – Updated: 2026-10-09 20:49

Title

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

Summary

Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account's password. An attacker who can obtain a token from the configured issuer carrying a victim's email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue.

Severity

7.5 (High)


                        
                          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

CWE

CWE-287 - Improper Authentication
CWE-290 - Authentication Bypass by Spoofing
CWE-345 - Insufficient Verification of Data Authenticity

Assigner

GitHub_M mitre root Scorecard

References

3 references

URL	Tags
https://github.com/go-vikunja/vikunja/security/ad…	x_refsource_CONFIRM
https://github.com/go-vikunja/vikunja/commit/7854…	x_refsource_MISC
https://github.com/go-vikunja/vikunja/releases/ta…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
go-vikunja	vikunja	Affected: >= 1.0.0, < 2.4.0

Show details on NVD website

JSON

To clipboard

{
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      "affected": [
        {
          "product": "vikunja",
          "vendor": "go-vikunja",
          "versions": [
            {
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              "version": "\u003e= 1.0.0, \u003c 2.4.0"
            }
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      ],
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        }
      ],
      "metrics": [
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            "attackRequirements": "PRESENT",
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            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
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            }
          ]
        },
        {
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          ],
          "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xv7q-fvmc-jx96"
        },
        {
          "name": "https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630",
          "tags": [
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          ],
          "url": "https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630"
        },
        {
          "name": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
        }
      ],
      "source": {
        "advisory": "GHSA-xv7q-fvmc-jx96",
        "discovery": "UNKNOWN"
      },
      "title": "Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover"
    }
  },
  "cveMetadata": {
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    "dateReserved": "2026-07-13T22:04:59.677Z",
    "dateUpdated": "2026-10-09T20:49:08.891Z",
    "state": "PUBLISHED"
  },
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          }
        ],
        "id": "CVE-2026-62367",
        "lastModified": "2026-10-13T21:17:39.863",
        "metrics": {
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                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
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                "version": "4.0",
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                "vulnIntegrityImpact": "HIGH",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "ssvcV203": [
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          {
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          {
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        "cna": {
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            }
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          },
          "title": "Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover"
        }
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        "datePublished": "2026-10-09T20:49:08.891Z",
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}

EUVD-2026-385239

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-09 21:44

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

JSON

To clipboard

{
  "assigner": "ENISA",
  "date_reserved": "2026-10-09T21:44:28.650663+00:00",
  "id": "EUVD-2026-385239"
}

FKIE_CVE-2026-62367

Vulnerability from fkie_nvd - Published: 2026-10-09 21:17 - Updated: 2026-10-13 21:17

Severity

7.5 (High) - 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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630
	security-advisories@github.com	https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0
	security-advisories@github.com	https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xv7q-fvmc-jx96

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "vikunja",
          "vendor": "go-vikunja",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.0.0, \u003c 2.4.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account\u0027s password. An attacker who can obtain a token from the configured issuer carrying a victim\u0027s email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue."
    }
  ],
  "id": "CVE-2026-62367",
  "lastModified": "2026-10-13T21:17:39.863",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
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          "attackRequirements": "PRESENT",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
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    },
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      "url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
    },
    {
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    }
  ],
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        },
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        },
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}

GHSA-XV7Q-FVMC-JX96

Vulnerability from github – Published: 2026-10-09 20:49 – Updated: 2026-10-09 20:49

Summary

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

Details

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:

// 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 warns about this at openid.go:388 ("Discouraged for untrusted providers where someone can set email without verification") — but enforces nothing.

Impact

Unauthenticated takeover of any existing local account (read/write/delete its projects, tasks, attachments, shares), bypassing the password. Scope notes: only issuer='local' accounts are matched (not pure-SSO users); the attacker's sub is not bound to the victim record, but the attack is repeatable; TOTP users are protected by the 2.3.0 enforceTOTPIfRequired gate (openid.go:250), non-TOTP users are not.

Preconditions

Admin enabled emailfallback: true (defaults false — a default install is unaffected).
The configured issuer lets the attacker assert the victim's unverified email: a self-service IdP (Keycloak/Authentik/Auth0/Dex with editable email), a mixed federation, or a multi-tenant Entra /common app. iss/aud are pinned, but the attacker controls email, not the issuer.
The victim has a local account.

Not reachable against a single-tenant IdP that verifies email and disallows self-set addresses.

Recommended Fix

Add email_verified to the claims struct and require it true on the email-fallback branch before linking to a local account; reject when absent/false. For Entra also require xms_edov and pin multi-tenant configs to an allowed-tenant list. Fail closed on an email collision not backed by a verified email from a trusted single-tenant issuer rather than silently logging the caller in.

Severity

7.5 (High)


                  
                    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

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.3.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "code.vikunja.io/api"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.0.0"
            },
            {
              "fixed": "2.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-62367"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-287",
      "CWE-290",
      "CWE-345"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-09T20:49:06Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n\nWith 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 \u2014 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\u0027s 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.\n\n## Details\n\nReferences 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:\n\n```go\n// openid.go:413\nsearches = append(searches, \u0026user.User{Issuer: user.IssuerLocal, Email: cl.Email})\n```\n\n`getUser` resolves this via `s.Get()`, which ANDs non-zero fields -\u003e `WHERE issuer=\u0027local\u0027 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 \u2014 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 warns about this at `openid.go:388` (\"Discouraged for untrusted providers where someone can set email without verification\") \u2014 but enforces nothing.\n\n## Impact\n\nUnauthenticated takeover of any existing **local** account (read/write/delete its projects, tasks, attachments, shares), bypassing the password. Scope notes: only `issuer=\u0027local\u0027` accounts are matched (not pure-SSO users); the attacker\u0027s `sub` is not bound to the victim record, but the attack is repeatable; TOTP users are protected by the 2.3.0 `enforceTOTPIfRequired` gate (`openid.go:250`), non-TOTP users are not.\n\n## Preconditions\n\n1. Admin enabled `emailfallback: true` (defaults false \u2014 a default install is unaffected).\n2. The configured issuer lets the attacker assert the victim\u0027s unverified email: a self-service IdP (Keycloak/Authentik/Auth0/Dex with editable email), a mixed federation, or a multi-tenant Entra `/common` app. `iss`/`aud` are pinned, but the attacker controls `email`, not the issuer.\n3. The victim has a local account.\n\nNot reachable against a single-tenant IdP that verifies email and disallows self-set addresses.\n\n## Recommended Fix\n\nAdd `email_verified` to the `claims` struct and require it `true` on the email-fallback branch before linking to a local account; reject when absent/false. For Entra also require `xms_edov` and pin multi-tenant configs to an allowed-tenant list. Fail closed on an email collision not backed by a verified email from a trusted single-tenant issuer rather than silently logging the caller in.",
  "id": "GHSA-xv7q-fvmc-jx96",
  "modified": "2026-10-09T20:49:06Z",
  "published": "2026-10-09T20:49:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xv7q-fvmc-jx96"
    },
    {
      "type": "WEB",
      "url": "https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/go-vikunja/vikunja"
    },
    {
      "type": "WEB",
      "url": "https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover"
}

Sightings

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Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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Action not permitted

CVE-2026-62367 (GCVE-0-2026-62367)

EUVD-2026-385239

FKIE_CVE-2026-62367

GHSA-XV7Q-FVMC-JX96

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